Holding(s) in Company

Porvair PLC
10 August 2005

Letter to: RNS

SECTION 198 COMPANIES ACT 1985 - 3% NOTIFIABLE INTEREST

We were advised today of the following holding by Prudential plc and certain
of its subsidiary companies.

Registered owner                         No. of shares               % holding

Prudential plc                               4,505,987                   12.24
M&G Group Ltd                                4,505,987                   12.24
M&G Investment Management Ltd                4,505,987                   12.24
M&G Limited                                  4,070,632                   11.06

Letter from: Chris Tyler
             Company Secretary


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