On Sun, 31 Dec 2017 12:35:38 GMT, Harry Bloomfield
wrote:

Dave Plowman (News) pretended :
A B&W TV can't show colour - other than that of its phosphor. Assuming you
are talking old CRT sets - not sure I've ever seen a B&W LDC, other than
tiny ones.

The BBC conducted some experiments in the 1960's, I think Tomorrow's
World might have been involved. Then of course all TV's were CRT, but I
did see a slight hint of colour, on a B&W CRT. Some saw nothing as I
remember.

I think I remember it, I couldn't see any effect but there always some
like my mum who reckoned they could. Did it involve in strobing the
image at certain rate? There was a craze for looking at hidden images
amongst a load of squiggles printed on paper about 20-30 years ago, I
could never see those either but others found them quickly, OTOH as
the printed pattern looked a bit like the ones sometimes printed on
paper surrounding sensitive information such as a salary slip and we
convinced a colleague that the within the pattern the company trade
mark could be seen and he then announced he could see it I've been a
bit skeptical as to how many were genuine.

BBC 4 returned to the subject in more recent times.
https://www.youtube.com/watch?v=3P8q_dCU3RI

G.Harman