Watching an old episode of The Sweeney on television last week, I was struck by how much rhyming slang – much of it politically incorrect – was used.

Who now would dare or wish to say ‘bubble’ or ‘lemonade’ in their homes, let alone on a popular television series? asks James Morton.

Back in the 1960s, some of my clients regularly spoke in this argot.

After constantly finding myself having to inquire what it meant when, for example, a client explained his absence from home by saying ‘I was going case with a mystery’ (or out sleeping with a girl), I decided to learn the vocab myself. A case keeper was a brothel keeper, but I never discovered the derivation of ‘mystery’, which specifically meant a Borstal absconder.

Possibly it was from the catchphrase of an old radio programme; could it be ‘mystery word – bird’? The actual rhyme itself was usually dropped.

I also made a fool of myself when one man, giving what he thought was an alibi, said, ‘I was on the river.’ Perking up, I said: ‘Oh, which river was that?’

‘Nah’, was the put down. ‘On the River Ouse – booze.’

One client couldn’t actually bring himself to speak in any other language. It was always: ‘Sorry I’m in a two and eight. Had a bull with the trouble in the frog outside. Them apples is hard on the plates. Nice whistle you’ve got Mr M.’ (This roughly translates as: ‘Sorry I’m in a state, I had a row with my wife on the road. Those stairs are hard on the feet. Nice suit Mr M.)

But one day he was arrested, and – so the police said – made a written confession that went something like: ‘I was having a Jimmy in the carsi when the pikey flashes me his groin and we’re swagged by the filth over some schmutter Tom.’

It would be easy to translate that little paragraph wrongly, but in fact it meant ‘I was urinating [Jimmy Riddle] in the lavatory [Italian for little house] when the gypsy [nowadays traveller but originally one who used the turnpikes] showed me his diamond ring [not an indecency charge] and we were arrested by the police over some fake [originally Yiddish for rags] jewellery.’

To confuse things, Tom can also mean a prostitute or to defecate.

The client was outraged. It was all a fit up.

‘You know it is Mr M. It’s all porkies. You know I don’t spiel like that’. It seemed to me one of those cases when he could never be allowed near the witness box.

James Morton is a writer and former criminal defence solicitor