Hello Stuart,
I too am lucky enough to own one of these boilers, and have also had the same problem of losing pressure, 1st thing to look at is your overflow/overpressure pipe, this normally comes out the side of your house(outside) and looks like a pipe with nothing on the end of it, if this is dripping with water the chances are the over pressure relief valve isn't operating properly, thus losing your pressure, if so operate the valve by rotating it 90deg and then release it, this will hopefully make it seal properly. Failing that you may have to replace the valve, that will cost about £25 for the part and 1/2 hours work, if its not the valve check your radiators arn't leaking ie this screw for bleeding them is tight, and if things are still bad you may have a leak in a pipe to or from your radiators, if your loosing pressure quickly its more of a concern because that water has to go somewhere?
Hope this helps
Paul.
Paul, March 2008
