Looks like Stockholm is Summer Time? CE(S)T
...and so is Britain. You can't go on the weather!
GMT is the non-summertime time. Britain is currently on BST (British Summer Time) which is equivalent to UTC (central universal time). Essentially,
whatever time it is in Britain, it is
always one hour ahead on CET, whatfer that pesky sun choochin around at it's own pace (<- Canadian).