The BBC did extensive testing before introducing colour.
In the first instance with NTSC RCA cameras. Huge things
with 3" IO tubes. Had a modification of NTSC to say 625
lines, 50 Hz been the way forward, they'd not have adopted
(and been part of the design) of PAL.

The BBC had little or no hand in "designing" PAL. The original NTSC proposal
/was/ PAL. Want proof?