Brits - Slang question: how do you say arrogant??

[Yeti]

cocky bastard/cocky t-word

[Eurotrash]

it doesn't quite fit the definition you need, but I think ponce might be a good one to consider.

[diebitter]

actually nonce isn't bad. It means 'pedophile' or kiddy-fiddler specifically, and a worthless person generally. Also easy to say and skate over without being picked up clearly.

I think the phrase that you are looking for is 'cocky tw_at'

[britspin]

Well, if the OP is taling to an arrogant author, perhaps He wants something a little more allusive than a insult direct, perhaps something that references the authors britshness.

Perhaps something like:

"I see the sun hasn't set on your self importance.."

"Congratulations- I hear you've recently been voted the 157th most important author in London"

"Mr X, tell me, when was it again you were on the NY Times beststeeler list?" (assuming he hasn't been)

"You know I always was told that we make everything bigger in america, like cars, steaks and skyscrapers. Of course, after talking to you I see how foolish that was. They clearly make the worlds biggest ego's over in england"