He said that anti-extremism measures, including the anti-radicalisation scheme "Prevent", had "overwhelmed the work on cohesion" since 2007.
While the Home Office is working on specific new counter-extremism measures, for other departments it is business as usual.
Counter-terrorism and counter-extremism measures don't have a great track record in terms of civil liberties but sometimes they work out for the best.
The prime minister appeared to support Theresa May, the home secretary, after the Guardian revealed a split in the cabinet over her counter-extremism measures.
"I understand why anti-extremism measures were taken but they were wrong to squeeze out cohesion measures," he said, arguing that the ongoing Casey review was a sign that the government knew it had got the agenda wrong.
While the immediate focus vis-a-vis Isis needs to be on practical counter-extremism measures, the west can no longer afford to turn a blind eye to Saudi's internal contradictions.
Up to 500 British jihadists are believed to be fighting with Isis in Syria and Iraq and the Government has increased counter-extremism measures in an attempt to prevent anyone else travelling to the conflict zones.
Cantle argued that a shift in focus by the previous Labour and then coalition government to anti-extremism measures "squeezed out" policies that were meant to promote community cohesion.
According to the letter, the home secretary, under counter-extremism measures, planned to introduce powers to scrutinise programmes before they are broadcast, with the ability to take pre-emptive action against them.
