The cheap long term option is to use a diesel CAV filter which has the added advantage you can see the fuel and any water in the filter through the glass section. They are available from Panda fuel Injection, just past Sainsburys in Fareham at £37. Replacement cartridges are £3 each. The CAV 196 filter is a very fine one and the 252 cartridge courser. Although they are not designed for petrol I have never had a problem and they have stopped water from getting into the engine particularly when the boat is being filled by jerry cans. Pic of the sort of thing here:
http://www.bosunsmate.co.uk/filters.htm
Back to the scrap yard at Bursledon me thinks
if you need a new one, shout and I will pick one up during the week from Panda for you.
Pete