SIR – Your left-of-centre correspondent, Christopher Hindle, is quite right to identify Russia’s real interest in Syria as being mainly to protect its highly-lucrative gas supply market into Western Europe.

At a more local level, I’m sure Mr Hindle will also have spotted the sudden arrival of the rag-tag rabble of ex-CND and ex-Greenham Common protesters at the experimental shale-gas fracking site in the South of England. Are these two issues connected? You bet they are.

If volume shale-gas extraction can be successfully achieved in Britain and Western Europe, then the demand for Russian gas will drop off the scale, so that nice Mr Putin has again sent in his regular ‘sleepers’ to try to preserve Russia’s cash-flow, by whatever stealthy means are available, even pretending to be anti-fracking nimby-types.

But Mr Hindle will also know this, so that’s something else upon which we can agree.

Graham Hoyle, Kirkbourne Grove, Baildon