OS X :: Difference In Analog And Digital Clock Time Display

I just bought a new MacBook Pro 15" running Leopard 10.5.6, and the clock is being weird. Last weekend we put the clocks forward an hour here in the UK and I suspect this has something to do with it. What's happening is that my clock is displaying an hour earlier than it actually is, and if I put it into manual mode rather than relying on the Euro Apple timeserver, that fixes it but then the time on my Mail is wrong - it says each message was received a hour before it actually was.

Then it gets really odd - if I change the timezone to London BST and then check the time & date panel, the digital clock still reads an hour early, but the analogue one beneath it displays the right time Then if I close the panel and re-open, I find it's reverted to GMT and both clocks say it's an hour early.