The government is considering scrapping gay people’s rights to civil partnerships rather than extending them to heterosexuals.

It has intervened before a Supreme Court hearing tomorrow when Rebecca Steinfeld and Charles Keidan, a couple with two young children, fight for the right to enter a civil partnership rather than having to get married.

Penny Mordaunt, the women and equalities minister, has commissioned research to find out if demand for civil partnerships is so low that the “government should consider abolishing or phasing out civil partnerships entirely”.

The paper, slipped out quietly in parliament, points out that the introduction of same-sex marriages in 2014 led to a slump in the number of civil partnerships. They averaged 6,305 from 2007 to 2013 but fell to a low