London: A quarter of British couples in a study said they have no idea how much their partner earns. Nearly 20 percent keep quiet about money matters until they take a step towards commitment such as buying a property together.

And 14 percent refuse to tell their partner what they earn until they have a child together. Even 19 percent of married people or those living together keep their finances a secret, the study found.

Londoners are the cagiest, with 31 percent not knowing their partner's salary. But in Yorkshire 81 percent are honest about finances, says the study.