The retired police officer claimed he warned the Government of a "perfect storm" of crime threatening the country before Britain begun to record an unprecedented number of knife and gun crimes.
There have been 66 murders in London alone since the beginning of the year, with police figures registering a 22 percent spike in knife crime and an 11 percent rise in gun crime across Britain.
Mr Brennan told talkRADIO: "Nobody was listening, nobody was acting, everyone was talking.
"Here we are now, the storm has hit Britain and in particular London we are now facing the effects of the tsunami.
EUROPARL TV•ITVUK news: Norman Brennan claimed to have warned authorities of rising crime years ago
"If I was to describe the overview in medical terms – I’ve already described it over the last five years, nobody listened and if they did they didn’t act – we are on life support: I’m telling you the family are around the bed."
The number of murders using a blade was up from