This lucrative little racket is providing the new generation of jailbirds with an extra source of pocket money.

The new trendies are approaching old lags with no knowledge of the drug scene and offering to sell them 'shit'.

But the product the pushers have to sell consists only of dried toothpaste and tobacco, which is passed off as shit.

The pushers, says Bill, have almost 100 per cent selling success.

Bill, who is not unknown to Newcastle drug squad, said: "You actually get some of them pretending to get high while the others are too frightened to admit they have been conned."

Talking about shit, it pays to be a good boy in Durham jail.

For the turnkeys have quite an effective way of dealing with those guys whose faces don't fit.

Every morning the prisoners leave their slops buckets outside their cell doors. The buckets are then collected and their urine and crap is poured down a pipe at the end of each floor.

But almost without fail, the pipes get blocked and the human effluent floods over onto the floor.

At this stage ("The smell is something rotten, especially when the wind blows your way", says Bill) the turnkeys select a prisoner who might have been a little cheeky the day before.

He is ordered to clear up the mess and unblock the pipe.

This punishment is old news to any journalists who ever spent a night or more in the jail while writing an eye witness account of what goes on inside.

The only trouble is that when they do stories like this their copy is always censored by the Home Office before their papers are allowed to publish.

Jules