You'd think that after the clock returned to Daylight Saving Time a little while back, iOS clocks would be back to normal, but no. Macworld is reporting that iPhone users in the UK are having even more issues with their device clocks, with some alarms not going off and others going off at the wrong time. At this point, the issue seems to simply be old versions of iOS out there -- Apple has, of course, been dealing with this one for a while, so the latest update to version 4.3.1 should fix the issues.
Britain also moved from Greenwich Mean Time to British Summer Time over the weekend, which could have caused some confusion. At any rate, if you had issues, make sure your iOS device is updated, and hopefully this will be the end of the problems we've seen with clocks.