Offer Update

Microgen PLC
30 July 2007


30 July 2007

NOT FOR RELEASE, PUBLICATION OR DISTRIBUTION, IN WHOLE OR IN PART, IN OR INTO
THE UNITED STATES OF AMERICA, CANADA, AUSTRALIA OR JAPAN OR ANY JURISDICTION
WHERE TO DO SO WOULD CONSTITUTE A VIOLATION OF THE RELEVANT LAWS OF SUCH
JURISDICTION

 Recommended Increased Cash Offer for the entire issued and to be issued share
       capital of Trace Group plc ('Trace') by Microgen plc ('Microgen')

                                  Offer update

Introduction

On 15 June 2007, the Microgen Board and the Trace Independent Directors
announced the terms of a recommended increased cash offer of 180 pence per Trace
Share (the 'Increased Cash Offer') which represents a premium of approximately
15.4 per cent. to the Tulip Revised Offer of 156 pence per Trace Share.

The Increased Offer Document was posted to Trace Shareholders on 20 June 2007.

Level of acceptances

Microgen announces that, as at 1.00 p.m. (London time) on 27 July 2007, the
fourth closing date of the Increased Cash Offer, valid acceptances of the
Increased Cash Offer had been received in respect of 2,860,898 Trace Shares,
representing approximately 20.08 per cent. of the Trace Shares.

The valid acceptances include 1,127,880 Trace Shares, representing approximately
7.92 per cent. of the Trace Shares, received pursuant to an irrevocable
commitment from Herald Investment Management limited and 10,000 Trace Shares,
representing approximately 0.07 per cent. of the Trace Shares, received pursuant
to an undertaking from Daniel Chapchal, Chairman of Trace, to procure acceptance
of the Increased Cash Offer of the Trace Shares held in his SIPP.

Microgen has acquired 3,680,000 Trace Shares in aggregate, representing
approximately 25.83 per cent. of the Trace Shares. Therefore, as at 1.00 p.m. 
(London time) on 27 July 2007, Microgen owned or had received valid acceptances
in respect of a total of 6,540,898 Trace Shares, representing approximately
45.90 per cent. of the Trace shares which it is entitled to count towards the
satisfaction of the acceptance condition under the Increased Cash Offer.

In addition, Microgen has also received an undertaking to accept the Increased
Cash Offer from Colin Clarke, a Trace Independent Director, in respect of the
1,426,453 Trace Shares (representing 10.01 per cent. of the Trace Shares) owned
by him and his connected parties upon the lapsing of his existing irrevocable
commitment to the Tulip Revised Offer. Such lapsing will occur in the event that
the Tulip Revised Offer lapses or is withdrawn.

Save as disclosed above, neither Microgen nor any person acting in concert with
it for the purpose of the Increased Cash Offer has an interest in (or a right to
subscribe for or any short positions (whether conditional or absolute and
whether in the money or otherwise), including any short positions under a
derivative, any agreement to sell or any delivery obligation or right to require
another person to purchase or take delivery in respect of) or has borrowed or
lent any Trace Shares during the Offer Period.

Trace Shareholders who wish to accept the Offer and who have not already done so
should:

(i)   in respect of Trace Shares held in certificated form, complete and return
      the BLUE New Form of Acceptance in accordance with the instructions
      set out in the Increased Offer Document and on the BLUE New Form of 
      Acceptance, so as to be received as soon as possible and, in any event, 
      by no later than 1.00 p.m. (London time) on 31 July 2007; or

(ii)  in respect of Trace Shares held in uncertificated form (that is, through 
      CREST), Trace Shareholders should submit a TTE instruction in accordance
      with the instructions in the Increased Offer Document for settlement as 
      soon as possible and, in any event, by no later than 1.00 p.m. (London
      time) on 31 July 2007.

This announcement should be read in conjunction with the Increased Offer
Document dated 20 June 2007 and the expressions used in this announcement
(unless the context otherwise requires) have the same meaning as in the
Increased Offer Document. The Increased Offer Document is available for
inspection on Microgen's website - www.microgen.co.uk and copies of the
Increased Offer Document and the New Form of Acceptance (for use by holders of
Trace Shares in certificated form only) are available for inspection during
normal business hours on any weekday (Saturdays, Sundays and public holidays
excepted) at the registered office of Clyde & Co LLP at 51 Eastcheap, London
EC3M 1JP until the end of the Offer Period.

Capitalised terms used, but not defined in this announcement have the same
meaning as given to them in the Increased Offer Document.

Enquiries:

Microgen plc                                 Tel: [phone]
Martyn Ratcliffe
Philip Wood

Arbuthnot Securities Limited                 Tel: [phone]                                             
(Financial adviser and broker to Microgen in relation to the Offer)
Ian Williams
Richard Tulloch

Financial Dynamics                           Tel: [phone]
(Public relations adviser to Microgen)
Giles Sanderson

Arbuthnot Securities Limited ('Arbuthnot'), which is authorised and regulated in
the United Kingdom by the Financial Services Authority, is acting exclusively
for Microgen and no one else in connection with the Increased Cash Offer and
will not be responsible to anyone other than Microgen for providing the
protections afforded to clients of Arbuthnot nor for providing advice in
relation to the Increased Cash Offer, or the contents of this announcement or
any matter referred to herein.

This announcement is not intended to and does not constitute, or form any part
of, an offer or an invitation to purchase or sell any securities or the
solicitation of any vote or approval in any jurisdiction pursuant to the
Increased Cash Offer or otherwise. The Increased Cash Offer is governed by the
terms of the Offer Document and Form of Acceptance as amended (in relation only
to the offer price per Trace Shares) by an Increased Cash Offer Document, and,
in relation to certificated Trace Shares, the new form of acceptance. Microgen
intends to dispatch such documents to Trace Shareholders (and, for information
only, to Trace Optionholders) shortly. The Increased Cash Offer Document and the
new form of acceptance will together contain the full terms and conditions of
the Increased Cash Offer, including details of how to accept the Increased Cash
Offer. Any acceptance or other response to the Increased Cash Offer should be
made only on the basis of the information contained in the Increased Cash Offer
Document and the new form of acceptance. The Increased Cash Offer will be
subject to English Law. The laws of relevant jurisdictions may affect the
availability of the Increased Cash Offer to overseas persons. Overseas persons,
or persons who are subject to the laws of any jurisdiction other than the United
Kingdom, should inform themselves about and observe any applicable legal and
regulatory requirements. The Increased Cash Offer Document is available for
public inspection in the United Kingdom.

Unless otherwise determined by Microgen, the Increased Cash Offer will not be
made, directly or indirectly, in or into the United States or by use of the
mails of, or by any means or instrumentality (including, without limitation,
facsimile, internet, email or other electronic transmission, telex or telephone)
of inter-state or foreign commerce of, or any facility of a national, state or
other securities exchange of, the United States, nor will it be made directly or
indirectly in or into Canada, Australia, Japan or any Restricted Jurisdiction,
and the Increased Cash Offer will not be capable of acceptance by any such use,
means, instrumentality or facility or from within the United States, Canada,
Australia, Japan or any Restricted Jurisdiction. Accordingly, copies of this
announcement are not being, will not be and must not be, directly or indirectly,
mailed or otherwise forwarded, transmitted, distributed or sent in, into or from
the United States, Canada, Australia, Japan or any Restricted Jurisdiction, and
persons receiving this announcement (including, without limitation, custodians,
nominees and trustees) must not mail, forward, distribute or send it in, into or
from the United States, Canada, Australia, Japan or any Restricted Jurisdiction.
Doing so may render invalid any purported acceptance of the Increased Cash
Offer. Any persons (including custodians, nominees and trustees) who are
overseas persons or who would, or otherwise intend to, mail or otherwise
forward, transmit, distribute or send this Announcement, the Increased Offer
Document, the New Form of Acceptance or any related document outside the United
Kingdom or to any overseas person should seek appropriate advice before doing
so.

Dealing disclosure requirements

Under the provisions of Rule 8.3 of the Takeover Code (the 'Code'), if any
person is, or becomes, 'interested' (directly or indirectly) in 1% or more of
any class of 'relevant securities' of Trace, all 'dealings' in any 'relevant
securities' of that company (including by means of an option in respect of, or a
derivative referenced to, any such 'relevant securities') must be publicly
disclosed by no later than 3.30 pm (London time) on the London business day
following the date of the relevant transaction. This requirement will continue
until the date on which the Increased Cash Offer becomes, or is declared,
unconditional as to acceptance, lapses or is otherwise withdrawn or on which the
'offer period' otherwise ends. If two or more persons act together pursuant to
an agreement or understanding, whether formal or informal, to acquire an
'interest' in 'relevant securities' of Trace they will be deemed to be a single
person for the purpose of Rule 8.3.

Under the provisions of Rule 8.1 of the Code, all 'dealings' in 'relevant
securities' of Trace by Microgen or Trace or by any of their respective
'associates' must be disclosed by no later than 12.00 noon (London time) on the
London business day following the date of the relevant transaction.

A disclosure table, giving details of the companies in whose 'relevant
securities' 'dealings' should be disclosed, and the number of such securities in
issue, can be found on the Panel's website at www.thetakeoverpanel.org.uk.

'Interests in securities' arise, in summary, when a person has long economic
exposure, whether conditional or absolute, to changes in the price of
securities. In particular, a person will be treated as having an 'interest' by
virtue of the ownership or control of securities, or by virtue of any option in
respect of, or derivative reference to, securities.

Terms in quotation marks are defined in the Code, which can also be found on the
Panel's website. If you are in any doubt as to whether or not you are required
to disclose a 'dealing' under Rule 8, you should consult the Panel.



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