I would agree that this year's fine summer has no doubt resulted in many more sightings of contrails over at least parts of the country. At the risk of stating the obvious, aircraft still contrail above the clouds when it's raining (as it often seems to do in West Wales in normal years) - you just can't see them then.
And the flightpaths that they are following when they cross each other have, in most cases, been there for decades, although of course the numbers of aircraft have been steadily increasing over the years.
So, much though I love a good conspiracy theory, I don't think there's one operating here.