Dear London Underground

"In this little book," explains the preface to Married Love, first published in 1918, "Dr Marie Stopes deals with subjects which are generally regarded as too sacred for an entirely frank treatment. Some earnest and delicate minds may feel apprehensive that such frankness in details is 'dangerous', because the effect on prurient minds might be to give them food for their morbid fancies."

Sadly, Dr Stopes's pioneering movement is still struggling to educate those earnest and delicate minds - most recently yours, the boys at London Underground, who have banned an "offensive" advertisement celebrating the family planning charity's 75th anniversary.

What on earth could be offensive about an ad for the world's most venerable family planning service, whose honorary sponsors include such controversial characters as Sir David Attenborough and the Rt Hon David Steel? The fact that it reveals - gasp - that Marie Stopes's services include company health screening, pregnancy advice and sterilisation? That it runs - shock - a clinic in central London?

Well, actually yes. Your poster people, now privatised and called Transportation Displays Inc, are particularly offended by the ad's use - in a short history of contraception - of the word "vagina" (the ancient Egyptians favoured plugging them with honey and natron). Also offensive, though slightly less so, you say, are the words "contraceptive pessary" (honey and elephant dung was a popular one in 9th-century Arabia) and "cervical cap" (Casanova made them using half a hollowed out lemon).

Marie Stopes International offered to withdraw the ad if there were lots of complaints. It even offered to black out the word "vagina". But no, the whole subject was branded too offensive to inflict on the capital's earnest and delicate Tube passengers.

"Offensive is always difficult to define," says your unfortunately named company spokesperson Jeremy Male, "but the Underground is a non-selective media choice. It may have caused problems for people travelling with children."

Funny old word, offensive. Funny how it doesn't apply to the ad's use of the words "condom" (probably named after a Dr Condom, who made one for King Charles II) and "sheath" (the Egyptians made them from animal membranes). I suspect that it is male Tube passengers who come over all earnest and delicate when faced with details of female anatomy; except when it's breasts, as in the totally unbanned Wonderbra ads.

Personally, what I find offensive is the level of hypocrisy and fear that still surrounds the subject of family planning 77 years after Marie Stopes first tried to clear the air, and the fact, therefore, that Britain has the highest teenage pregnancy rate in Western Europe. Not to mention the totally unearnest and indelicate men who make Tube travel a nightmare, morning (groping), noon (ogling) and night (vomiting).

RUTH PICARDIE