[ceebee23]

I think primary reason for the BBC and the UK not adopting 405 line NTSC was that the EBU had settled on 625/50 as the new European standard in the early 1950s.

This was being progressively introduced across Europe (both west and eastern Europe). (Australia adopted this standard in 1956)

France was running an 819/50 and the UK its 405 line standard both were phased out by the early 1980s.

The UK decided to introduce colour with the 625 line standard. Various investigations into the colour format were undertaken and ultimately PAL was adopted.

But the key to the decision not to proceed with 405 NTSC seems to have been cost and a fear that if they adopted 405 line NTSC colour the public would have seen less reason to adopt the spanking new 625 line standard ... because on the colour receivers of the day 405 line, 525 line and 625 line looked barely different!

I should also point out that the commercial broadcasters, especially ITN's Lord Grade were pushing heavily for colour from the moment they went on air!