Yes, as Rayna says, he should file for divorce here in UK
His grounds will be living apart for more than 5 years.
Should be really quite straightforward and cheap. He can do himself without any problem just fill out the forms.
No need for any legal representation.

Take a look here:-
https://www.gov.uk/divorce/overview

It'll only be a few weeks to process.
Just read through the above webpage and follow the appropriate links