From the BBC:

The Children’s Minister has ordered a review of the case of two police officers told they had broken the law by caring for each other’s children.
Ofsted said the arrangement contravened the Childcare Act because it lasted for longer than two hours a day, and constituted receiving “a reward”.
It said the women would have to be registered as childminders.
Minister Vernon Coaker said his department was talking to Ofsted about this particular case.
According to the Mail on Sunday, Ofsted told two detective constables, Leanne Shepherd, from Milton Keynes, and Lucy Jarrett, from Buckingham, to end their arrangement. . . .
“They just want to return to work after having children and have found that the system is working totally against them.
“They’ve been threatened with prosecution by Ofsted if they continue doing this.”
An Ofsted spokesman said it applied regulations found in the Childcare Act 2006, but was currently discussing the interpretation of the word “reward” with the department for Children, Schools and Families (DCSF).
“Reward is not just a case of money changing hands. The supply of services or goods and, in some circumstances, reciprocal arrangements can also constitute reward.