Under (the) Covers Unit?

Kit Jackson would like some help with information about a little-known family planning unit. He writes:

My father, long since deceased, said that as he was unfit for war duty, one of his duties was to head up a unit whose task it was to encourage the women of Great Britain to use condoms. There were two reasons: married women were becoming pregnant even though their husbands were away, and also with the advent of black US and Canadian servicemen, there was the so-called “brown baby” syndrome.

Have you heard of this unit? Were there really worries about mixed-race children? Please do get in touch.