How should someone with a German PhD be addressed in the UK? This question has been discussed several times but there doesn't seem to be a clear answer for my particular situation.

I have a Dr.rer.nat from Germany but currently I am working for an institute in the United Kingdom. Is it legal or acceptable to continue to use the title Dr.rer.nat (First Name) (Last name) in the UK or do I need to change it to (First Name) (Last name), (Ph.D)?
In the UK the holder of a PhD (or other professional doctorate) will generally use the title Dr as opposed to Mr/Mrs/Miss that would normally be used.

Unlike in Germany there is no addition to field of study.

Therefore the correct title would be Dr (First Name)(Last Name).