“It is possible that women, particularly post-menopause, do not use condoms because they equate condom use with preventing unwanted pregnancy rather than prevention of STIs.

“Similarly, men over 50 who may have had a vasectomy in their 30s or 40s may not consider using condoms with a new sexual partner,” Dame Sally says.

Diabetes risk

The report also warns that the figures may be an underestimate as older people may be unwilling to seek treatment or seek help outside the NHS to avoid the stigma of attending Genitourinary Medicine clinics.

The report also warns that a “startling” eight in 10 older women are so fat they are at risk of diabetes.

Figures show 80 per cent of female baby boomers and 75 per cent of men of this age have waistlines so large they put them at risk of the condition.

A waist larger than 35 inches for women or 40 inches for men is considered a risk factor for diabetes.

The figures show that morbidity from diabetes has risen by 97 per cent among men and 57 per cent among women aged 50 to 69 between 1990 and 2013.

Risks linked to lifestyle factors such as obesity, diet and low physical activity rose by 70 per cent over the period, with 45 per cent of all cases linked to “modifiable” factors.