RNS Number:4985M
Schroder Investment Management Ltd
18 June 2003

                                                                      FORM SAR 3

Lodge with a RIS or Newstrack and the Takeover Panel. A copy must also be sent
to the company the shares of which are acquired.

Date of disclosure:     18/06/03

   DISCLOSURE UNDER RULE 3 OF THE RULES GOVERNING SUBSTANTIAL ACQUISITIONS OF
                                SHARES ("SARs")

Date of acquisition     17/06/03

Acquisition in          Porvair Plc
                                    Number of shares over shares       If rights over shares acquired, as
    (1)     Class of voting shares  acquired                           opposed to the shares themselves,
    (e.g. ordinary shares)                                             specify nature of rights

            2p ordinary shares                10,467 shares






                                      Resultant total holding of rights           Total percentage
    (2)     Resultant total holding   over shares (and % of total
    of voting shares (and % of total  voting shares in issue)
    voting shares in issue)

8,102,035 shares (22.014%)                                                            22.014%


 (3)     Party making disclosure     Schroder Investment Management Limited
                                                      Schroder Investment Management Limited on behalf of
        (4)     (a)     Name of person acquiring      institutional clients on a non-beneficial basis
        shares or rights over shares and, if
        different, beneficial owner


             (b)     Names of any other persons
        acting by agreement or understanding (see SAR
        5)


Signed, for and on behalf of the party named in (3) above

(Also print name of signatory)     Duncan Murray

Telephone and extension number     020 7658 2962 (Direct line)

                          ___________________________

Note.     Under SAR 5, the holdings of and acquisitions by persons acting by
agreement or understanding must be aggregated and treated as a holding of or
acquisition by one person. Note 3 on SAR 5 requires persons who must aggregate
holdings to disclose certain disposals.

For full details of the SARs disclosure requirements, see Rules 3 and 5 of the
SARs. If in doubt, contact the Panel on Takeovers and Mergers, Tel. No.: 020
7638 012


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