I can clear this up - I sat on the government/industry committe that decided how the paternity leave regulations work.
The answer is: his employer is wrong.
You can choose to nominate a particular date for paternity leave to start, or you can nominate the birth as the start.
If you choose the birth, then it really is that - the birth triggers the start of paternity leave.
NB - NOT LABOUR (we all know there are false starts!)
When you go into labour, your husband can leave work to be with you using "Emergency time off for dependents", which is unpaid, but guarantees the right of people to leave work when there is an emergency with someone who is dependent on them (the legislation explicitly includes labour). Paternity leave does not start until the baby is born.
He should tell them that paternity leave will start when the baby is born. Not on the due date, and not when the labour begins.
He should NOT tell them he is going on paternity lave when you go into labour - you never know, labour can stop and it could be a week before the baby is born, and you don't want him to have triggered paternity leave early.
If his employer disputes this, he should just say that they are welcome to try their case in an industrial tribunal, but the tribunal would throw their case out - the legislation is very specific on this point (we went to some lengths to ensure that the government didn't make these kinds of mistakes when designing paternity leave).
So...
- nominate the birth as the trigger
- take unpaid emergency time off when you go into labour
- when the baby is born, phone up work and tell them paternity leave has just started, and he's got two weeks off from that point on.
Hope this helps