Offer Update

NOT FOR RELEASE, PUBLICATION OR DISTRIBUTION IN WHOLE OR IN PART IN OR INTO THE
UNITED STATES, CANADA, AUSTRALIA OR JAPAN.

                             Recommended Offer by                              

                              UBS Investment Bank                              

                                 on behalf of                                  

                                 Microgen plc                                  

                                      for                                      

                                AFA Systems plc                                

Offer declared unconditional as to Acceptances

The board of Microgen plc ('Microgen') announces that as at 3.00 p.m. (London
time) on 8 September 2004, being the First Closing Date of the recommended
offer ('Offer') for AFA Systems plc ('AFA') as set out in the offer document
dated 18 August 2004 (the 'Offer Document'), Microgen had received valid
acceptances of the Offer in respect of a total of 40,187,678 AFA Shares
representing approximately 85.17 per cent of the existing issued ordinary share
capital of AFA.

Prior to the announcement of the Offer on 13 August 2004, Microgen had received
irrevocable undertakings from the AFA Directors and irrevocable undertakings
and non-binding letters of intent from certain other AFA Shareholders to accept
the Offer in respect of a total of 22,731,692 AFA Shares, representing
approximately 48.18 per cent of the existing issued share capital of AFA. Valid
acceptances have been received in respect of 22,669,229 AFA Shares subject to
the irrevocable undertakings and non-binding letters of intent and are included
in the total number of valid acceptances referred to above. Valid acceptances
in respect of the remaining 62,463 AFA Shares subject to the irrevocable
undertakings and non-binding letters of intent have not yet been received.

The board of Microgen announces that the Offer is declared unconditional as to
acceptances. The Offer remains subject to the terms and conditions set out in
the Offer Document dated 18 August 2004. Microgen has convened an EGM for
10.30am on 10th September 2004 for Shareholders to approve the Resolutions
relating to the Offer and its implementation.

The Offer will remain open for acceptance until further notice. The closing
date for the Mix and Match Facility is 3.00pm (London time) on 9th September
2004 and no elections under the Mix and Match Facility received after this date
will be valid.

Forms of Acceptance not yet returned should be completed and returned in
accordance with the instructions set out in the Offer Document and in the Form
of Acceptance so as to be received as soon as possible. If AFA Shares are held
in CREST acceptance should be made electronically so that the TTE instruction
settles as soon as possible.

Save as disclosed in this announcement, the Offer Document and the listing
particulars in respect of New Microgen Shares which accompanies the Offer
Document, ('Listing Particulars') prior to the commencement of the Offer Period
on 13 August 2004, neither Microgen, nor any persons acting or deemed to be
acting in concert with Microgen, held any AFA Shares (or any rights over AFA
Shares) and neither Microgen nor any persons acting or deemed to be acting in
concert with Microgen, have since acquired or agreed to acquire any AFA Shares
(or any rights over AFA Shares).

Unless the context otherwise requires, defined terms used in this announcement
shall have the meanings given to them in the Offer Document and Listing
Particulars.

This announcement does not constitute an offer or an invitation to purchase or
subscribe for any securities. The Offer is made solely by the Offer Document
and the Form of Acceptance accompanying the Offer Document, which contain the
full terms and conditions of the Offer, including details of how the Offer may
be accepted.

The Offer is not being made, directly or indirectly, in or into, or by the use
of mails or any means or instrumentality (including, without limitation,
telephonically or electronically) of interstate or foreign commerce, or any
facility of a national securities exchange, of the United States, Canada,
Australia or Japan and the Offer cannot be accepted by any such use, means,
instrumentality, facility or otherwise from within the United States, Canada,
Australia or Japan. Accordingly, copies of this announcement, the Offer
Document, the Form of Acceptance and any accompanying documents are not being,
and must not be mailed or otherwise distributed or sent in, into or from the
United States, Canada, Australia or Japan and persons receiving such documents
(including nominees, trustees and custodians) must not distribute or send them
in, into or from the United States, Canada, Australia or Japan. Doing so may
render invalid any purported acceptance of the Offer.

The availability of the Offer to persons who are not resident in the United
Kingdom may be affected by the laws of the relevant jurisdictions. Persons who
are not resident in the United Kingdom should inform themselves about and
observe any applicable requirements. Further details in relation to Overseas
Shareholders are contained in the Offer Document.

The New Microgen Shares to be issued in connection with the Offer have not
been, nor will they be, registered under the Securities Act or under the
securities laws of any jurisdiction of the United States, nor has a prospectus
in relation to the New Microgen Shares been lodged with, or registered by, the
Securities Commission of any province or territory of Canada or the Australian
Securities and Investments Commission or the Ministry of Japan. Accordingly,
the New Microgen Shares may not be offered, sold, resold or delivered, directly
or indirectly, in or into the United States, Canada, Australia or Japan or any
other jurisdiction outside the United Kingdom in which the offer of New
Microgen Shares would constitute a violation of relevant laws or require
registration thereof.

UBS is acting exclusively for Microgen in connection with the Offer and no one
else and will not be responsible to anyone other than Microgen for providing
the protections afforded to clients of UBS or for providing advice in relation
to the Offer or in relation to the contents of this announcement or any
transaction or arrangement referred to herein.

Microgen                                                                       
Mike Phillips, Group Finance Director                                          
                                                                               
Phone: [phone]                                                            
                                                                               
UBS Investment Bank                                                            
Nick Adams                                                                     
                                                                               
Phone: [phone]                                                           
                                                                               
Financial Dynamics                                                             
Giles Sanderson                                                                
                                                                               
Phone: [phone]