I've had some more replies to my query Charles:
"Pres B, in the days before the start of colour TX, was used as a test bed for colour cameras. Rehearsals were used to evaluate the colour system being tested. For transmission the programmes were in black & white, achieved by switching off the colour subcarrier. "
"It did happen Bill. I was the Vision Operator for most of a series called "The First Lady", with Thora Hird (1968/69). At that time only BBC2 was in colour and I remember working with just the luminance tube of the 4 tube Marconi colour cameras. These were not to last long, the EMIs being greatly superior. The one thing the Marconis did well was black and white pictures - probably the best ever seen in studios. I remember a partly coated mirror (or prism) was removed from the optics after the lens. This enabled us to work at half the light level used for colour, reducing the number of shillings in the electric slot!
That saving and a limited amount of colour post production availability led to the decision to work in B&W.
I am sure other programmes were made this way - I vaguely remember Blue Peter as one.
The rest is lost in 45 years of fog and dry ice!"
"Yes there were - I think it was in the period when there were a number of colour studios but BBC1 was still monochrome. I remember working on a crime series starring an Italian who didn't speak English that well - can't remember the name of the show - and that was recorded in TC1 with EMI 2001s in monochrome. It seemed odd at the time."
I think that the crime series referred to above is "Vendetta" starring Stelio Candelli
http://www.imdb.com/title/tt0159927/. I seem to remember it had a signature tune written by John Barry.
I assume the studio engineers could switch off the colour subcarrier I am no expert I'm afraid.
I suppose it is possible that some monchrome recordings may contain the colour information as you say.
Bill