By Jon Silverman Home affairs analyst

Jamaicans coming to the UK now need visas. The move is seen as part of efforts to crack down on violent street crime. So how does Jamaica fit into the picture? Last week, the Home Office imposed a visa requirement on Jamaican visitors to Britain. Coming in the wake of the murder of two Birmingham girls in what the police believe was a shootout between rival gangs, the announcement must inevitably be seen as linked to the debate about drugs, crime and the gun culture.

You've got to be tough with them like the Americans are Police informer, Suzy

So, where does the island of Jamaica fit into all this? The views of a Jamaican who has spent a large part of her adult life as an informer for the police on both sides of the Atlantic are instructive.

Suzy was born in a Kingston ghetto, Tivoli Gardens, lived for many years in New Jersey and is now resident in London. She is blunt and totally unsentimental about the propensity for violence of some of the Jamaicans she has known intimately.

"These guys will shoot federal agents in the US. They'll shoot policemen in Kingston. They are dangerous and vicious criminals and when it comes to protecting their drugs turf, they will do almost anything."

The violent crime statistics in her native Jamaica bear this out and when the heat is on from the police and army, the gunmen make a swift exit abroad.

The visas scheme follows the killing of Latisha Shakespear (right)

"In the early days of crack cocaine, they went to the States. These guys formed the so-called 'posses' and they prospered.

"But then the authorities got tough and handed down long terms in federal penitentiaries and deported them when the sentence was over. So, they started coming to the UK, where the cops didn't carry guns and the crack market was just opening up."

Last November, Jamaica's Commissioner of Police, Francis Forbes, said that some of the island's most violent criminals used the UK as a safe haven, flying on false documents and returning home when things "had cooled down".

Revenge attack

A recent kidnapping in Bristol led to a tit-for-tat abduction in Jamaica. It is for this reason that Jamaican and British police officers are stationed in each others' countries and that customs and immigration officers are forging closer links.

US authorities got tough

The press which serves the black community in the UK has long reflected disagreements over the influence of Jamaican nationals on crack dealing and gang rivalry. When the police used to describe certain criminals as Yardies, commentators sensed a lazy racism at work.

And as Operation Trident in London enters its fourth year, the evidence shows that the majority of suspects are British-born rather than Jamaican. But the extent of the influence of Jamaica and its highly individual culture is still an open question.

Suzy says some of the men she knew in Jamaica became more dangerous as a result of going to the United States. "America glorifies violence and the drugs world there, particularly the Colombians, is really vicious. So, some of these guys got their crime education in the States and they brought what they learned to Britain. "

Operation Trident has focused on crime in inner London

But a study of recent Jamaican history shows that since at least 1980, the gunmen have had almost an honoured role in enforcing the will of one or other of the two main political parties. One famous piece of footage from the 1980 election shows a man firing a pistol as though he is an extra in a Western.

Over the years, Jamaican gunmen have occasionally brought the same recklessness to UK streets and at the same time as the Birmingham murders, Eli Hall was keeping a squad of armed police at bay in the Hackney siege and vowing not to be taken alive.

Suzy says longer prison terms are an answer. "Some of these guys can't read or write and couldn't even spell Mercedes. But they understand weakness and they exploit it. You've got to be tough with them like the Americans are."

Maybe. But while the profits from crack dealing are so immense, the potential for violence will remain.