@Twigletmama, yes, if you can care for your children yourself at home then you can furlough your nanny as not needed. Some of my friends with jobs that have got quieter or with older children doing this - and while the balance is hard, financially most will end up better off than usual, as the govt will ultimately reimburse up to £2500/80% of the wages paid each month.
However in our case, for example, we have young DCs and both work full time, and managing the crisis has meant long days that are not flexible. We initially tried having our nanny off on full pay, but it was not possible for us to care for them and work.
My work has said that they still require me to work full time. I cannot claim to my own employer that I need to be furloughed due to lack of childcare when that is not true, and even more I cannot then put her on furlough and claim she's not needed. Doing this would be fraud on the taxpayer, as it is entirely legal for her to come. (Even if it were not fraud, this would cost the tax payer £5000 a month and lose a significant further amount of tax paid in).
I would therefore otherwise have to quit. In which case I could legally pay her furlough until the scheme ends, after which she and I would both be unemployed, in the middle of a major recession.
And yet she is totally isolated, as are we, other than weekly supermarket shops and brief walks to the park and to work. What is the benefit to society or to us in stopping this?