I assumed it was just a reverse print-like the cover of Bob Dylan's first LP. [You can only tell by looking close-the strings are reversed. He's never been left handed]. Or are you being serious Graham?
I didn't know about these BBC 405 line colour ambitions for a long time. I started a thread based on a 1966 WW article "405 v 625 COLOUR" [2/5/12] which reported on a BBC technical and customer consultation. They decided in favour of 625 lines but it looked a bit disingenuous to me as the punters couldn't see much difference. I suspect that other political and economic factors were in the mix
Dave W