"I once sat in a barbers in Luton having what little hair I still have cut. A radio was playing what I believe was R1, I didn't recognise any of the music so it probably was. Often aircraft RT could be heard although the barber said 'it's the police again'. From what was being said it had to be 121.270 (TC NW) "
Sounds like a classic case of what is called "IF breakthrough" to me.
Domestic radios often use 10.7Mhz as an 'intermediate frequency' before being converted to the audio we hear.
Without being too technical, the 'image frequency' of 2x10.7, i.e. 21.4Mhz higher (or lower) is also recieved, but blocked by 60, 70dB or more (this is the 'IF image rejection' often seen in the technical spec of the radio).
However, this may not be enough if the transmitter on the image frequency above is close enough for the image signal to still be heard despite that 60dB (or one million times) reduction.
In the case above, 121.270 minus 21.4 = 99.87Mhz, plenty close enough to the upper part of the Radio 1 allocation to have potential for IF breakthrough.