Forms of masculine address in contemporary Britain (aka: a little problem I have writing Sherlock)

So, let me ask you about a problem I have writing Sherlock!fic:

What casual epithets--non-name words--do contemporary British men use to address each other?

An American guy (depending on the situation) would say: "man," "dude," or "buddy"; or, given the right age difference, "son," "kid" or "kiddo"; or, more rarely, "chief," "sport," "tiger" or "bro'."

And an ACD-era British man might use endless permutations of: "old chap," "dear fellow," "old boy" (or even, as in the Ritchie movie, "old cock"); and, in certain situations, "my dear" or "my friend."

But what do British men say nowadays?

"Lad"? But people who are the same age don't really use this with each other, do they?

"Boyo"? This is too Irish, right?

"Sunshine"? I love this one, but it seems very regional (Northern) and old-fashioned to boot.


So, what do y'all (as even Yankees say in the South), what do y'all think:

Is having all these other forms of address just an American verbal tic (one that was more common in previous generations of British menfolk?)--A dialogue crutch from which I just happen to get unreasonable amounts of pleasure?

Or are there ways John and Sherlock (or Benedict and Martin) would address each other than "John" and "Sherlock"?

(and yes, I know the whole thing must be riddled with class connotations--enlighten me!)

Thanks in advance!