Sam, wot time is the TP server set to (i.e. European time or GMT +2) as i just noticed there some time ago that i have posted a thread and it said posted at '0859 on 14th dec' and i know that i didnt do it at that time locally, here in Ireland. dont worry not a prob im just curious!!!
The server is in California, so it is set to their time.. PST I think they call it.
Perhaps you can set the time to GMT and put a footnote with the message "All times are GMT".
Or if you have the time, allow members to set their GMT offset in the profile and display the times and dates of forums posts according to that when they log in.