Does noone know about time zones?
CEST is GMT + 2 (Summer)
CET is GMT + 1 (Winter)
BST is GMT + 1 (i.e. all Summer you have NOT been on GMT)
GMT is followed by UK only in Winter.
The concept of Summer Time was, I believe, introduced in the 1st World War to increase productivity at a time when daylight was more essential to many jobs and, as today, just to get up earlier or later was asking too much of the average Briton (restrictive drinking laws came in for the same reason, productivity).
Until the railway/fast transport age, everywhere used local time based on when the sun reached the highest point in the sky, meaning that there could be a ten minute time difference or more between the Easternmost and Westernmost places in UK - made time-tabling interesting. Note, for those rabbitting on about Scottish farmers: time zones are East to West (sideways!), not North to South, hence South Africa is on the same time zone as UK and New Zealand is twelve hours ahead. Edinburgh is further West than Exeter (old trick question at school), so the West Country and Wales should be in the same zone as most of Scotland and different from London, perhaps (I like that idea, one could say that it is all ready the case culturally).
As for computers: I am sure that it is just as easy to set your TZ to CET/CEST as to GMT/BST, at least I have got the technical knowledge to do that, or even, under UNIX, to set my own time zone settings.
Personally, I would either set the whole of Europe, East or West, on CEST or on GMT The big advantage of time zones is cultural; as a general rule, working hours are about 0800 -1700, give or take half an hour, everywhere. With a single time zone, one would have to remember that, in say, Austria, working hours are (Summer) 1000 to 1900, in NZ, 2000 -0500 ... That may be harder to remember than just a simple offset from GMT.and culturally much harder.
After all, GMT was agreed as a defining point not for everyday clocks but for coordination of international travel and understanding. It was done, not for nationalistic reasons but mainly pragmatic ones, such as most sailing charts at the time were produced by the United Kingdom (it being the majore maritime power, commercially and miltarily at the time) and these referred to Greenwhich as 0 and were most widely used throughout the sailing world.
I believe that the British forces use GMT wherever they are in the world for obvious reasons.
There is a place called Britain, or Bretagne - not a country though many of its inhabitants may wish it were so.