Question Author
Thank you all,
the hospital I was taken to was an Isolation Unit in Hyde (now Greater Manchester) which primarily housed tuberculosis patients, so not a private establishment. My wife thinks it's hardly likely that given the scale of the epidemic in those days, the powers-that-be would have bothered to cheer the babies up with an ambulance painted like an ice-cream van. I think she's probably right, I was very ill and very young, the 'memory' could have been some sort of hallucination, which has stuck in my mind. By the way Dee, reference your Mum's haircut, the other thing the Authorities sometimes did was burn all the child's toys and books and bedding etc., and fumigate the house, sometimes even stripping the wallpaper Anyway, thank you all for your kind attention to this weird request, Google was unable to help!
thanks from greenrook