here is the actual government document.
http://www.direct.gov...IntoTheUK/DG_10026136
As I said you are allowed 186 days in the UK in any one tax year, Your work must be all overseas and the company you work for must be based overseas.
I worked like this for 7 years in Africa and the Middle east.
The only things you need to be careful about are the time in the UK, just an hour over the limt will land you a tax bill, and not doing any work at all inside the UK. I know of people who agreed to make a few technical visits while they were back home on leave in UK and they got taxed !