Disappearing Harlequin Ladybirds?

Some years ago, there was a great to do about the rise of the Harlequin Ladybirds. I took part in reporting sightings, and photographed quite a few colonies over wintering in parts of our house.

For the past few years they have been noticeable by their absence here in deepest Finchampstead. This past winter I saw one, roosting in the window frame.  The winter before I can't remember seeing more than about three - one of which was dead.

Sightings in my garden have also been diminished. I think I have spotted four at most; three of those in the last fortnight. I have actually spent more time in my garden than the previous years.

Are these ladybirds suffering the same crash in numbers as seen with other insects or have a few harsh winters done for them?