You can blank them all you want once you've given them your correct name and address, if they request it and SUSPECT your ticket is invalid.
To refuse, as I'm sure you know, is a criminal offence.
Believe me, there are a good number of the argumentative type that have no interest in taking details, favouring the dinosaur attitude of "I'm not listening to you, pay up or get off my train." A paying customer should not have to put up with that. Some ticket inspectors deal with things in a less ethical way to others.
Back when I could be asked to converse with these hard head types, I had the BTP called on me a few times over silly fare disputes, in all of which the ticket inspector rejected my suggestion of taking my details and dealing with the dispute properly. Every single time, I turned the situation around so that it was the ticket inspector the BTP started questioning, instead of me. Quite a few of them failed the attitude test with the BTP too. I actually pitied them as it was a sorry, embarrassing thing to watch, them losing their temper with the police at work - but they chose to create the situation for themselves.
There is a power to request name an address, but there needs to be a
reasonable suspicion that another byelaw has been broken as I'm sure you know. I was taught not to abuse the powers bestowed when I worked in revenue protection. If you've been shown written evidence that your initial suspicion was wrong but choose to persist, I wouldn't rely on the BTP to cart off someone you call on them - that customer might do a good job of convincing the police that your suspicion and behaviour was unreasonable. Probably better to be nice and provide good customer service instead - or stick to using powers against actual fare evaders, not calm natured people who take the time to explain why their ticket is valid to you and show you proof.
What is the best tactic to play with gatelines and do you mean entering or leaving a platform?
If they won't let you leave when you have a valid ticket, call the BTP. If you don't have the time on your hands, you'll need to think of some other way to leave the station which doesn't have potential to land you in trouble. Where there's a will, there's always a way. On other occasions, I've telephoned the relevant manager, who has then instructed them to open the gates. Not always an option to everybody, granted.
Getting in is a bit more difficult. Not much you can do if you're refused travel, especially as station staff tend to close ranks even if the initial colleague dealing with it was wrong.
Of course, staff can avert these awkward situations by giving the benefit of the doubt, listening and being reasonable or simply getting it right first time. A situation is as difficult as you allow it to become.