The information in the IS files obtained could halt the movement of fighters and help prevent attacks in the West.
The most valuable aspect of the Islamic
State files obtained by Sky News will be the details of the terror
group's recruiting network.
The details have the potential to halt the movement of fighters to Iraq and Syria and also possibly help prevent attacks in the West from IS devotees trained to target their home countries, Ramsay said.
Referring to the group's sponsors, he said: "There's going to be the core that are in Turkey, but then there will be others in Europe, we think North America as well, and certainly in Britain.
:: IS Documents Identify Thousands Of Jihadis
Ramsay said that while IS has changed tactics to focus on recruiting people to stage attacks in their own country, the group's sponsors still play a role.
"There has been a slight change, they (the sponsors) are nowadays wanting to recruit people to attack in their own country rather than come to fight the war," he said.
"That is a tactic that we identified some time ago and that will continue.
:: Who Are The Britons In The Islamic State Files?
"But I still think for the authorities the terror network, the facilitators of the movement into Syria, will still be part of the network even if they're doing other things. They'll still be there."
The documents contain tens of thousands of names, addresses, telephone numbers and family contacts of IS jihadis, and also who recruited them to the group.
Nationals from at least 51 countries, including the UK, had to give up their most personal information as they joined the terror organisation.
:: Islamic State Files: 'Goldmine Of Information'
The man who stole it was a former Free Syrian Army convert to IS.
Major General Chip Chapman, a former head of counter-terrorism at the Ministry of Defence, told Sky News the cache of documents has huge value to the security services and is disastrous for IS.
"They've given us the treasure chest and they've given us the key as well."