The only reason I would have to visit Longleat would be to see their Siberian Weasel, if they are still extant - and this is not reason enough on its own.
Unfortunately Boulas still has to be on his own, I photographed him this morning. I don't know how you tell whether a gorilla is happy, but it's nice surroundings and he's safe.
It is very difficult(impossible?) to get strange Silverbacks to live together. If they can't get him with the other males he may be destined to live alone longerterm, either at Longleat or elsewhere, as moving him would not solve the problem of integration either.
Not sure how much the presence of the other gorillas might stress him but at least he has not got people staring at him from close quarters now, think he might like that.
In his case this may be true, but some apes appear to like interaction with the visitors, so in certain situations surely removing this from their daily routine as well as moving them to a new home might simply add to the stress?
Of course some do and would really miss it but I didn't feel Boulas liked being stared-at at all.
Most normal adult Gorillas, particularly adult males that haven't been humanised in infancy, hate being stared at. Its a threatening gesture and makes them feel uneasy.
So the spaciousness and distance from people, of Longleat's enclosure might suit him a lot better in that respect. I doubt he actually wants to be with other males though, but he might be missing his former female companions. Having said that, I still think Twycross made a sensible decision to move him and consolidate their Gorillas into one small group. I also think Oumbie (at Twycross)is probably less stressed without Boulas so closeby.
But plucking his arms/hair is a sure sign of some sort of stress, particularly when he never did it previously. As I said above, I know of no instance where two adult stranger silverbacks have ever been successfully integrated together- male groups are normally formed with one adult and several juvenile males, or a group of same-aged males that have grown up together- and even these arrangements don't necessarily work when they reach full maturity.
So if Longleat succeed in adding him to the others it may be a first, though a solitary life in sight and sound of other Gorillas, as with Nico, may now prove the only option for him.
IMO Twycross should never have accepted Boulas from Belfast- who needed to move him out as he is apparently infertile. Without him Twycross could quite possibly have consolidated the others into a single group when Oumbie first arrived, and also avoided yet another move for Boulas.
I imagine Boulas is still owned by Howletts(where he was born) but they didn't need him either and the group of males he used to live with at Port Lympne has since been dispersed, as the other males were sent to different Zoos abroad.
So the Longleat option probably mirrors what would have happened if he had gone back to PL. Unfortunately males in his situation are difficult to house satisfactorily, he could well end up as another Nico which is rather sad given he has been a group leader until now. But I don't see any other realistic option for him at present.
Probably at the time Boulas arrived at Twycross there were no plans to convert the gorilla house into chimpanzee accommodation and they were going to continue with two groups, this is before it became obvious that the new "state of the art" chimp facility was not going to materialise,.
One could argue that Boulas could have ended up in a similar social situation if he had been a wild living gorilla -- unsuccessful silverback gets ejected from group by another male, ends up alone or on the peripery of a group. Not all wild animals are alpha males, not all alpha males stay that way. So, evolution ought to have set him up, psychologically, for his current situation. Appropriate interaction with keepers and enrichment ought to redress some of the loss of a social group.