Thousands of council officers will patrol bars, restaurants and shops to police the smoking ban when it comes into force in July.
Councils have been granted #29.5 million to pay for staff, who will be able to issue on-the-spot #50 fines to people and take court action against premises if they flout the law.
A BBC investigation found that the officers will be able to sit among drinkers undercover and photograph and film people. A Government-funded course is expected to train 1,200 council employees in the next few months, followed by more later.
Ian Gray, policy officer for the Chartered Institute of Environmental Health and chief trainer for the government course, told the BBC: "I expect most councils will take a softly, softly approach at first.
"But there will be some occasions where action has to be taken and I am sure the officers will not shy away from that.
"These officers do not have to identify themselves when they go into premises and they can even film and photograph people to gather evidence although this may not be appropriate in many cases."