The remaining third of those aged 16 to 22 say they are attracted to those of the same sex at least some of the time, although nearly half of these – 14 per cent – say they are ‘mostly’ heterosexual.

That contrasts with 88 per cent of baby boomers – people in their 50s and 60s – who say they are heterosexual and 6 per cent who are mostly so.

The stark generational shift in how people view their sexuality emerged in research carried out for the BBC by pollsters Ipsos Mori.