We have a nanny, and are in a very fortunate position to eb able to afford it. She works three 11 hour days a week looking after DS1 (5yo) and DS2 (1yo). It is the only form of childcare that works for us, as DH works long and unpredictable hours, I leave early in the morning and I sometimes have to work late. We both have a 2 hour commute each day.
Childminders don't start early enough every day or work late enough on occasion to be an option. Nurseries and before/after school clubs aren't an option for the same reason. Our nanny is great. We also don't have problems covering school holidays and she will look after our DC if they are unwell, take them to the doctor etc. She has also on occasion taken them for haircuts, new shoes, have passport photos taken etc, and she is a great help to me at home with doing the DC's laundrty, some cooking etc. Its flexible care, and it works really well for us.
I don't want to say our combined salary on here as I know it will get peoples backs up. As I say, I know we are in a fortunate position. I don't begrudge our nanny our salary (and I understand that you wouldn't either OP). She works hard and she deserves that salary. My gripe (obviously not directed at her at all) is that we have to pay her salary and NI out of already taxed income. Unlike a business. I think this is something that the government should change.
Also (and I get that you see this too OP), I think everyone should look at childcare costs as coming out of the parents' combined salaries. Childcare is a shared expense. It should not be seen as just coming out of the mother's salary. Very often I see mums saying something along the lines of "I earn £X, and I pay £Y in childcare which means that I work for £Z per week". If you have a career, or a job you enjoy or need or whatever, you are working so that you have that job or career in the future, when your childcare bills may have reduced. And work is about more than money.
Have you thought about having a live in nanny? Their wage would be reduced as they have their rent etc paid. Might work if you ahve a spare room.
Also, look into you and your DP being paid the maximum anmount you can be in childcare vouchers, and employ an Ofsted registered nanny so that you can pay her/him partly using those vouchers. It makes a difference.
IME, nanny shares can work very well. But be aware that a nanny working as a nanny shre will command a higher salary than a nanny who works for one family (even if she is looking after the same number of children). Sure, it would be less that you would pay for sole charge, but it won't be half.