Mr Heath in his letter of April 5 asks “where have all the insects gone?”

Much the same concern applies to the strange decay of lead roofs on historic buildings and the spikes in autism and dementia cases recorded since the Nineties. The decline in insects may also have led to a reduction in birds.

The answer may have something to do with “chemtrails”. Sky watchers started noticing new, persistent aircraft trails in the Nineties.

Hitherto, aircraft trails, known at the time as contrails, short for condensation trails, lasted about 20 seconds before dissipating.

Since the Nineties however, most trails have been persistent and merge to form overcast skies.

These trails cannot be made of condensation as they don’t dissipate and indeed portray many signs of being chemical aerosol sprays.

These new trails are known as chemtrails, short for chemical trails, a term apparently first used by the US Air Force.

I have written to Professor Dame Sally Davies, chief medical officer for England to ask for assurances the trails are not chemicals or if they are, have been been authorised by Parliament and subjected to the most rigorous assessments for risk to human health and the environment and independent scientific review.

She denied we are being sprayed with chemicals. I don’t believe this denial and conclude chemtrails are indeed a danger to life.

Overcast skies in themselves are a danger, because of reduced light levels leading to skin conditions and theoretically at least, a reduction in crop yield (probably offset by yet more chemicals in the form of fertilisers).

With the help of the UK Chemtrails Project, I carried out a rainfall analysis in my garden in Harwich, the results of which confirm aluminium oxide, a known cause of dementia, and a cocktail of other chemicals are present in the air we breathe.

The same chemical signatures can be duplicated anywhere in Europe and other parts of the world.

I found another clue on a recent visit to China where a comment about the permanent overcast skies over the large cities of east China was met with this answer from a general: “don’t you criticise our clouds, we need them to protect us from the latest American weapons”.

Stephen Dixon

King’s Head Street, Harwich