A Kent MP says the criminalisation of smoking in cars carrying children will waste valuable police time – as officers are forced to go on “fag patrol”.

North Thanet Tory Sir Roger Gale described the move as “unenforceable” after fellow MPs backed the amendment yesterday by a majority of 269.

The vote gives health secretary Jeremy Hunt the power to enforce a ban on smokers lighting up when youngsters are in the car.

But after voting against introducing the measure, former smoker Sir Roger said: “This law is ill thought-through and unenforceable.

“Setting aside the nonsenses that were exposed during the debate – which of two 17-year-olds in a car is going to be criminalised?

“The young driver or the young smoker? It has always been a sound parliamentary principle that law that cannot be enforced should not be allowed onto the statute book.

“I cannot see the Home Secretary, who also voted against the measure, wanting to waste her police officers` time trying to work out who in even a stationary vehicle might or might not have been smoking and when.

“Put that vehicle onto a motorway at speed and it becomes clear that the proposed ban is nothing more than political posturing.”

“This is another instance of the nanny state seeking to substitute itself for parental responsibility and the state has never been a good or an effective parent....” - Sir Roger Gale

The Labour-supported amendment received the backing of 700 health experts, but Sir Roger says smoking in the presence of children is a matter of “personal judgement”.

He said: “I have not smoked for 30 years myself, I loathe smoking in public places and my wife, who does still smoke, would never dream of smoking even when I am present in our own home, much less in front of our grandchildren, either in the house or in a car.

“That said, this is a matter for education and common courtesy and good manners as much as it is about health.

“Common sense says that it has to be a bad thing to subject children to passive smoking but that is a matter for personal judgement and not for the criminal law.

“This is another instance of the nanny state seeking to substitute itself for parental responsibility and the state has never been a good or an effective parent.”

“We certainly need to seek to prevent young people from smoking and we also need to protect them from the harm caused by secondary inhalation.

“But we are not going to achieve that by criminalising the idiots that care so little for their kids that they are prepared to kipper them in the Ford Mondeo and by trying to get a police force with other priorities to drop their enquiries and to go out on ‘fag patrol’.

“I happily voted for the remaining Lords’ Amendments relating to plain packaging and other measures, but I draw the line at knowingly voting for bad law.”