HC Deb 28 June 1950 vol 476 c225W
69. Mr. Storey

asked the Postmaster-General why he has prohibited the use of air mail envelopes with coloured borders

Mr. Ness Edwards

The Post Office is medically advised that the use of envelops with multicoloured borders is undesirable as they are a potential source of eye-strain. There is also a risk of their causing delay by mis-circulation of overseas letters other than surcharged air mail and of inland letters if, as could not be prevented, the special envelopes were used for such correspondence.