Rule 8.3 - ISOTRON

FORM 8.3

DEALINGS BY PERSONS WITH INTERESTS IN SECURITIES REPRESENTING 1% OR MORE
(Rule 8.3 of the City Code on Takeovers and Mergers)


1.      KEY INFORMATION
Name of person dealing        BARCLAYS PLC
(Note 1)
Company dealt in              ISOTRON
Class of relevant security    ORD GBP0.25
to which the dealings being
disclosed relate (Note 2)
Date of dealing               20 December 2006


2.      INTERESTS, SHORT POSITIONS AND RIGHTS TO SUBSCRIBE

  (a)   Interests and short positions (following dealing) in the class of relevant
       security dealt in (Note 3)

                            Long                    Short

                      Number       (%)        Number       (%)

(1) Relevant        329,364       1.53%          0        0.00%
securities
(2) Derivatives           0       0.00%    240,361        1.12%
(other than
options)
(3) Options and           0       0.00%          0        0.00%
agreements to
purchase/sell
Total               329,364       1.53%    240,361        1.12%


(b)     Interests and short positions in relevant securities of the company, other
     than the class dealt in (Note 3)

  Class of                          Long                            Short
  relevant
  security:

                    Number                      (%)              Number                 (%)

  (1) Relevant
  securities

  (2) Derivatives
  (other than
  options)

  (3) Options and
  agreements to
  purchase/sell

  Total


  (c)   Rights to subscribe (Note 3)

Class of relevant security:   Details



3.      DEALINGS (Note 4)

(a)     Purchases and sales

Purchase/sale Number of Securities Price per unit
                                   (GBP)
Sale          8,024                Transfer
Sale          34,442               Transfer
Sale          5,205                Transfer
Sale          118,844              Transfer
Sale          233                  Transfer
Sale          8,610                Transfer
Sale          25,833               Transfer
Sale          490,725              Transfer
Sale          25,966               Transfer
Sale          9,003                Transfer
Sale          90,101               Transfer
Sale          1,274                Transfer
Sale          4,267                Transfer
Sale          14,312               Transfer
Sale          10,921               Transfer
Sale          55,641               Transfer
Sale          41,615               Transfer
Sale          17,886               Transfer
Sale          5,127                Transfer
Sale          2,572                Transfer
Sale          23,016               Transfer
Sale          6,389                Transfer
Sale          7,356                Transfer
Sale          8,012                Transfer
Sale          13,348               Transfer
Sale          16,94                Transfer
Sale          2,891                Transfer
Sale          4,550                Transfer
Sale          60,597               Transfer
Sale          9,766                Transfer

(b)     Derivatives transactions (other than options)

Product    Long/Short    Number of Securities  Price Per
name,      (Note 6)      (Note 7)              Unit (GBP)
e.g. CFD
CFD        Short         240361                Transfer


(c)     Options transactions in respect of existing securities

(i)     Writing, selling, purchasing or varying

Product name,   Writing,          Number of          Exercise  Type, e.g.      Expiry   Option money
e.g. call       selling,          securities to      price     American,       date     paid/received
option          purchasing,       which the option             European etc.            per unit (GBP)
                varying etc.      relates (GBP)


(ii)    Exercising

Product name, e.g.  Number of           Exercise price per
call option         securities          unit (Note 5)




(d)     Other dealings (including new securities) (Note 4)


Nature of transaction Details           Price per unit
(Note 8)                                (if applicable)
                                        (Note 5)





4.      OTHER INFORMATION

Agreements, arrangements or understandings relating to options or derivatives


Full details of any agreement, arrangement or understanding between the
person disclosing and any other person relating to the voting rights of
any relevant securities under any option referred to on this form or
relating to the voting rights or future acquisition or disposal of any
relevant securities to which any derivative referred to on this form is
referenced.  If none, this should be stated.





Is a Supplemental Form 8 attached? (Note 9)                             NO


Date of disclosure                        21 December 2006
Contact name                              BARCLAYS COMPLIANCE
Telephone number                          020 7116 2913
If a connected EFM, name of
offeree/offeror with which connected
If a connected EFM, state nature of
connection (Note 10)


Notes

The Notes on Form 8.3 can be viewed on the Takeover Panel's website at
www.thetakeoverpanel.org.uk