Europe/London is just the PHP timezone for the UK, and it changes from GMT to BST and vice versa in Mar/Oct, so at the moment it's BST.
The fact that the time is correct on the Last Updated column in the tabular open ticket summary view but not within the individual tickets themselves presumably means that the right variable is available, it's just not being used in the latter case? If so then if you can tell me the correct variable name to use, and which variable it should replace and in which file, then presumably I could patch the issue?
Thanks