I used to think that a parent's care was unequivocally the best childcare, but I no longer believe that to be true. As the mother of a four month old who has had 95% of her care provided by either me or my husband working from home, and 5% by a grandmother coming to stay and watch her, I have learned that having a dedicated child care person is not only vastly superior for the working parents' productivity/quality of life, it is also superior for the child. My daughter made so many developmental strides while under the full attention of an adult, versus the divided, frazzled attention she received from a working parent. Having come to the realization that my bright and inquisitive daughter needs more than the partial attention of an adult, we have changed our minds about our ability to care for her while performing our jobs (work in my case, professional school in my husband's).

You might therefore consider what we are currently considering in our single-income household, which is to get an au pair. I am in the US, so program details/costs will differ, but here is my assessment based on the U.S. program. Since they are live-in, the cash outlay can be considerably less than getting a nanny. While there are substantial program fees, their salary is paid at minimum wage, which is generally half to a third (even a quarter) of a nanny's wage. If you live in an expensive area, the cost of an au pair can even be competitive with in-home daycares (which are typically the least expensive type of daycare). Other benefits include their childcare training from the program, the light housework they may perform, and the "cultural exchange" aspect of hosting a young adult from another country.

(If an au pair doesn't work out for us, our second choice would be to do a nanny share.)