Haven't found a definitive answer on this here, but in the UK we have summer and winter times, however many Economy 7/10 tariffs don't change. I assume (maybe incorrectly) that GMT will change for DST and UTC will not?
Its worth double checking as my eco7 times were not what I thought, look up your Time Switch Code and be a little late and early with the timings as it doesnt appear to be that accurate on the older meters.
Thanks,
Dupe...