In James Cordens biography, he said they spent every single day together for three years including Christmas day etc then when Gavin and Stacey finished, they never spoke again.
Apparently Matthew is quite difficult. His take was that when he plays a character, for the whole time is he that character and will live as that character so when he finished as Gavin, he had no need to carry on living as h and that it was the end of the chapter of his life so he no longer had a need to be friends with James.
Quite sad really as it seems James valued the friendship more than Matthew did.
I mean we should bear in mind that this is very much from one perspective. Ask any two friends why they fell out and you will always get two different stories...
That said, looking back at that time, it sort of seemed like of the two of them, Matt Horne was the one destined for super stardom. He wasn’t the brains of the show but he was the face - and a pretty one at that. It would have been less easy to predict James corden going on to conquer America as he has. Matt Horne has basically faded into obscurity as well.
How hard it must be to maintain a friendship, and a working relationship in such an intensely competitive ego driven field? Remember they also had a sketch show “Horne and corden” (or something) that was a huge flop, absolutely crucified in the press? I can imagine them blaming each other for that, feeling held back, wanting to focus on a career alone etc and it worked for one ...
Them doing the Xmas special is a sign the relationship has repaired a bit. Though from corden’s perspective it’s easy to be gracious in success, returning having conquered Hollywood and all that ...and Horne probably needs the work...