Sperm donations through licensed clinics have gradually been falling since the law changed in 2005 giving rights for donor children to know the identity of their biological fathers on turning 16 and 18.  

This has put off many would-be donors – in fact one sperm bank in Birmingham had to close altogether in 2017 after donor numbers fell to just nine in two years.  At the same time, demand for donated sperm has been rising, as social attitudes towards both single parenting and gay relationships and marriage have changed.  

Little wonder that single women, lesbian gay couples and heterosexual couples with...