No coverage by Which? unfortunately, as they are often useful in such matters.
But trawling through the archives here I did find several other threads, all useful, and one comment stood out, from a member called Burncycle (I think), who seems no longer to be around.
Anyway, the comment was on the lines of anyone buying a bike for £1.5-£2K and then scratching around for cheapo insurance wasn't being very consistent; and he compared it to buying a decent car and then getting it serviced by a bloke in his garden shed.
Points hit home - I had a glance at my various household policies, and it does seem that breakdown cover for cookers, washing machines, boilers, and so on, runs at about ten per cent of their new prices, so those quotes approaching £200 aren't that far off the mark.
(Yes, I know it's not for breakdown cover, but it's probably unlikely that the oiks will be breaking in and carrying off my Miele, so it is a similar proposition).
My lifelong mistrust of insurance companies is undiminished, but I think I'm going to have to bite the bullet and pay the going rate, AND buy a big heavy chain to carry around with me.
Such is life.
Allen.