Frankly, at £10 per hour, I do expect housework as well as childminding, but I have always made that clear from the start. Although I also make it v clear that DD comes first ie no housework if she is awake.
If I was only paying £5-6 per hour, wouldn't expect anything beyond babysitting, but £10 per hour changes things for me.
As it is, I have a full time nanny who we pay £8 per hour (plus tax and NI makes it approx £11.30 gross per hour), which makes her more expensive per hour than OP (£10 per hour gross) but I understand that to be a competitive rate in central London.
And being even more strident, I would find another babysitter if I was presented w a bill for the ironing at the end of the month. Admittedly, the most I ask for is 5 shirts to be ironed and some general tidying, but that's not the point - don't think its reasonable for a babysitter on £10 per hour to object to doing housework. Not had a problem finding a willing babysitter, either.
Again, apologies if this seems harsh, OP, just being frank.