Kamikaze
UK is 240 too, 220V is the continent.
Kind of. Officially the entire EU is meant, by treaty, to move towards a harmonised single EU standard in lots of technical fields. Mains supply voltages being one, the idea being that if something works in one member state it will work in all. However, because replacing every electrical item in the EU would be both expensive and impractical and there's no technical reason to do it the Directive that implements the treaty allows for quite a bit of leeway when member states draw up their mains supply laws.
So the current law in the UK says that delivered mains voltage must be at 230V with a leeway of between +/-10%. Which conveniently means nothing in the UK has to change. The other EU member states have their own laws with similar leeway to mean they actually have to change nothing. This is one reason why e.g. laptop, synth and effects power supplies are generally switched mode, unlike a transformer circuit the switched mode can supply the same output over a big range of mains voltages and what works in the UK will therefore also work in e.g. Germany (plug differences apart).
The household voltage we get tends to be around 235-242V, which is pretty much what it was when we moved here 30 years ago.
(this post provided by TriviaRus).