Partnerships Between Uk And Thai Universities

I know that many Thai universities have arrangements with UK (and I am assuming US and EU) universities where the Thai students do the first 2 years of the degree at the university here in Thailand following and then transfer to the partner uni in the UK and do another 2 years and at the end they graduate with a UK degree.

I was wondering how the 2 universities go about arranging and setting these partnerships up and how would a small UK uni seeking a partnership with a Thai university go about this?

Also I'd like to know what the legalities are and what kind of paperwork is involved.