Because the police asked him if he wanted help in stopping this happening and he told them he could manage. He also drew up a list of what he'd do to stop it going on but the licensing committee felt that as he hadn't done anything previously despite being offered assistance by the police then there was little chance of him doing anything unassisted.
Seems sensible enough to me, he probably didn't want it stopped as the reviews of this pub were less than flattering to say the least and the travellers were providing him with an income.
If you can't control your pub and refuse the help offered, of course you are going to have your licence revoked. That's why they have licensing in the first place. To ensure that the proprietors keep their premises under control and within the rules. He didn't, no more license, no surprise.
I've seen this in the past. They would have smashed the pub up if he told them they were not welcome. The only way to sort this out would have been to get whatever help he could get from the Police and to get several really huge doormen at the pub for a couple of months. He has the right to refuse to serve whoever he want's but, in this situation, he need's plenty of muscle to allow him to do that and it costs. It's the old adage that you will always win through if you are a lot bigger than they are.
We had a similiar problem in a pub called The Kicking Cuddy in Coxhoe. The pikeys would congregate there before moving on to Appleby fair. The villagers were terrorised by the scum. In the end Durham police went in mob handed and turfed them out and told them if they ever returned thier 1960's untaxed transits would be impounded and they would be held untill the horse fair was over. Theres been no trouble since and its a decent pub now.
There is a little old pub in Hertfordshire, close to where I used to live, where it was not unusual to see one of the girls/ladies from the nearby stables ride their ponies into the bar. The regulars and the landlord were totaly unfazed by this, and would feed the horses apples and sweets. I never heard any complaints from the passing trade, especially if they had youngsters with them. Just remember "It`s not what you do, it`s the way that you do it"