When I made my ITV documentary "The Rise of the E-cigarette" for ITV Tonight in January last year, the devices were widely seen as far from mainstream.

I was repeatedly told by experts (including the World Health Organisation) that we should take great care not to encourage their use because too little is known of their safety and effectiveness.

How things have changed.

Today, we got the closest we have ever seen to an official endorsement of e-cigarettes.

Public Health England says they are 95 per cent safer than smoking normal cigarettes, and recommends that they be made available on NHS prescription for those wanting to quit tobacco, once they have been licensed as medicines.

Public Health England says vaping is 95 per cent safer than smoking normal cigarettes Credit: PA

Today's report puts health officials in the dock. Why are they so far behind the curve on this vital public health debate?

This has been a revolution led by consumers - the 2.6 million-odd "vapers" who use -cigarettes.

Innovation has been led by the (often small) firms who brought them to market with zero official support.

Now, the spotlight must fall to the World Health Organisation, the NHS and the British Medical Association - will these authorities shift their stance?

Read: E-cigarettes 'should be prescribed on NHS', say health chiefs