Devices have not adjusted their time...

[GaryM]

I have 2 x Echo units and one Spot but none have gone forward an hour.  They are all set to the correct location and set to GMT.

I'll try a reboot but anyone know what to do if that doesn't work?

Found it.  You have to change the time setting for each device to British Summer Time. Bit of a pain they can't do it themselves considering they are online...

[AlanH]

All of my devices adjusted to the correct time automatically.

[StevenR]

Mince adjusted fine as well. I think I have had the issue previously, and it was caused by using just a non-geographic timezone like "Greenwich Mean Time (GMT)" (which don't automatically adjust) rather than a geographic one like "Greenwich Mean Time (London)" time zone (which do).
If you want to change it now, the time zone is now called "British Summer Time (London)".