Question Author
Thanks everyone. Lots of good points.
Possibly I wasn't very clear. My friend will get her pension paid by the German government, but, if we leave, only in Germany. She could arrange to transfer a certain amount every month to her UK bank, but the German system is that they pay tax and Social Security on their pension. So, she would be losing quite a lot of money for a health system, roads, police etc in Germany, that she is not using, as she lives in the UK.
Just to make things more 'interesting' at the moment she is losing up to €100 a month because of the Euro/pound exchange rate. She's caught between the proverbial rock and hard place whatever happens.
What I was hoping for was someone who knew someone else in the same position who could put her onto some useful German websites.
But again thanks folks.