This is what I can buy in Germany:
http://www.karstadt.de/shop/ats_150_tauchsieder.asp

They're not common here. I'd suggest buying one from Germany, either next
time you are there or over the internet. Some things are just about
impossible to obtain in the UK, like metric only measuring tapes, which I
normally pick up from Carrefour or similar!

The equivalent over here is a travel kettle, presumably because of superior
safety.

Christian.