The .270 minimum advisory in the HOG is for an initial grant or variation where the primary 'good reason' for the rifle is to shoot wild boar. It does not apply to previously authorised firearms which already have the AOLQ condition attached.
In the absence of any primary legislation for wild boar common sense should prevail in an individual's choice of calibre/chambering to do the deed.
This, in my opinion, is where the AOLQ condition fails. I feel the .270 recommendation is there for good reason, and I think licenses should be conditioned accordingly. Whether the 270 is accepted as a minimum calibre, is another thing.
When the AOLQ condition was first introduced, "Herts" conditioned licenses for the biggest quarry you had permission for, with the AOLQ condition intended to allow anything below, trying to make sure that the FAC holder had a calibre suitable for the job.
My FAC is conditioned this way, boar, plus AOLQ, and there is no mention of deer. Clearly, whilst their intentions are good, this system is obviously flawed.
Watching You Tube footage of the US using 223's to shoot boar/hogs, and taking up to 4 shots to do the job, I'd hate to see that happening over here, and injured animals running around the countryside, just gives ammunition to the anti's !