Where is Perkins Generator Company Headquarters located?

Question

in the UK

Answer 1

http://www.diamond-brothers.com/generator.html
says it is a sister company of Caterpillar.

http://en.wikipedia.org/wiki/Perkins_Engines
says they are a subsidiary, but that they were formed in Peterborough, England in 1932,

http://www.cat.com/cda/layout?m=37391&x=7
has the address for Cat, in Peoria, Illinois, USA