Why did the UK allow jihadis to operate for so long?

The Daily Telegraph published an important report on American assessments made of terror suspects held at Guantanamo Bay between 2002 and 2009. 
The report is based on classified American documents that were written by senior US military commanders, and leaked recently by Wikileaks. 
They show how American authorities identified London-based hardline Islamists, like Abu Qatada and Abu Hamza, as being al-Qaeda recruiters, and how no fewer than 35 Guantanamo detainees "passed through Britain" - more than any other Western state -before ending up in Afghanistan where they took up arms against allied forces. 
According to the Telegraph, the documents illustrate "how, for two decades, Britain effectively became a crucible of terrorism, with dozens of extremists, home-grown and from abroad, radicalised here... The files will raise questions over why the Government and security services failed to take action sooner to tackle the capital’s reputation as a staging post for terrorism, which became so established that the city was termed ''Londonistan.''”
As I have detailed in my recently published book, Virtual Caliphate, jihadis have used Britain as a base to organize and fund terrorist attacks for decades. Yet Britain itself was not attacked until the multiple suicide bombings in London on July 7, 2005.
Why did al Qaeda’s UK branch suddenly decide to turn on its host? 
The answer lies in a jihadi concept known as the covenant of security, a concept that has been openly discussed on English-language al-Qaeda affiliated websites, and which I explore in my book. 
It is a formula that al-Qaeda affiliated members use to determine whether their host country should be left alone or attacked.
According to the jihadi internet forums, the covenant of security in the modern, caliphate-less era is a modus operandi that allows for them to live in "Western infidel countries" in a state of ceasefire. 
Unfortunately for the host countries, the covenant of security spells out a most shaky truce, one that seems destined for failure.
When the UK government did finally pass more stringent anti-terror legislation, forbidding incitement to terrorism, British-based jihadis declared on the internet that the covenant of security had been violated. Another act of betrayal, they said, was the “taking of hostages”— a reference to the arrests of jihadi operatives on terrorism charges.
British police placed al-Qaeda recruitiers figures in jail, such as Abu Qatada. His followers viewed the arrest and conviction as "hostage-taking."
The new legislation passed against them, and arrest of their senior figures, spelled the end of the covenant of security for jihadis, they said. 
But was Britain ever an unofficial party to "the covenant" before it ended? According to a high-ranking British politician, there are indeed suspicions that such an informal agreement did exist between the British government and jihadis in Britain in the past. 
In June of 2007, I interviewed Baroness Caroline Cox, former deputy speaker of the House of Lords, who was visiting Israel at the time. 
Cox said there were signs that the UK government allowed jihadis into Britain and gave them a free hand to set up base, on the understanding that Britain would not be harmed. 
My recently published book, Virtual Caliphate, takes the reader into the heart of al-Qaeda''s online presence.