And what is your answer to your own question so far, pure? Ds obviously has relatively limited childcare at 5 days a fortnight, but it's still feeling pretty unworkable. In Ireland, where I'm from, far more mums go back at the 6 month mark and go back f/t but there tends to be a lot more family support with many having access to grandparent care etc.
I don't think that you can roll back to a time when one parent didn't work for many reasons. I personally feel a certain moral obligation to work, although I don't do much of it. The NHS paid for my degree as a mature student, my job is specialist and I am not easily replaced, that has an impact on other people etc. If all I had to consider were theories of attachment, maybe dh and I could have both reduced to one wage and split our work.. but financially, we would have struggled and it's just not feasible for the workforce to consist of only 50% of the parent population.
As an adult, I have learned that money is sometimes quite important really, not just "seeming" to be. I think it's the easy option in analysing this to assume it's about consumerism/materialism. We live in a 2-bed ex-council house in an area that is quite average, drive a 3 door ford fiesta (1 car), only go abroad to visit family (pretty important in the grand scheme of things). As a professional, my wage is technically decent, but it doesn't really cover the lifestyle you might imagine it would. I really want us to be in a position to move to a 3 bed in the future, and to have a garden for a dog. That, as an aspiration, is not about money really. I want to have three children and yes, we could put them in one room and yes, there are parks if you don't have a garden and very fine kennels where you an borrow a dog for an afternoon. However, my parents managed what I dream of on much less money than I earn. It's one of the great lies of this type of debate on MN/in the media that because technically, people can scrape by on minimal wages that anyone who works does so for consumerist reasons. A lot of people are concerned for financial security, as they ever were, but the price of general goods and houses etc are much higher in relation to average income than they once were.
I think, and I speak professionally here, that some of the attachment stuff is overblown. I know quite a bit about this area, and can tell you that on any assessment, ds would rate as being securely attached to both dh and I, with me as primary attachment person - and is, in fat, much more securely attached than when he began nursery (which reflects his development - started nursery at 12 months having had no childcare etc). According to Biddulph et al, he shouldn't be away from a primary attachment figure at all at this point.. but I think humans are quite adaptable, and as long as they are loved consistently and have someone who loves them consistently, the likelihood of negative outcomes based on attachment is probably negligible.
None of which solves my need for alternative childcare for when ds is ill if I am to keep my job..