I've been thinking the same thing. Try google he may have switched to a forum with more HO'ers. If he's posting he'll turn up.
Jon us still around and taking layouts to shows, he is on Facebook but not sure if he is on any forums now.
If you are on Facebook just search for Sweet home Chicago or Sweet home Alabama. Or indeed Jonathan Grant
I noticed he was on the forums but my wife tracked him down on Facebook. We visited him in England while we were over in December and had a nice time chatting and seeing his excellent work. He let me do a little running on his Sweet Home Chicago layout and also ran his VIRGINIAN layout he acquired that was featured in the July 2014 issue of Model Railroader.
My wife and I visited John Grant in Dec 2014 while over in England. I've noticed since then he has largely disappeared from posting on MR forums and a few others. My wife has him on FB and from what she said, he has a new girlfriend and well, that probably says a lot! LOL A lot less trains.
Yeppers. Looks like a female has distracted Jon Grant from his trains. Hopefully he will be able to find balance in the Schwartz and do some modeling.