Consulting can take a toll on home lives. In some instances, we expect our consultants to travel at the drop of a hat. This is one reason, important but not the only one, why there is often a feeling of a consultant / admin divide.
You should do what you can to minimise this. It can be corrosive to culture when consultants feel that non-consulting staff have it easy, or develop an air of superiority. We don't want to build an us-and-them culture where office has the "easy" job and works from home whenever.
So my take with admin and operational staff was that they should be in the office during working hours. Clearly, there was some human flexibility - if they need to be home for the laundry man, etc.
But this flexibility didn't extend to being at home to keep an eye on the kids (not very PC, but unless it was exceptional, e.g. with a sick child, then flexibility didn't mean you did childcare while working). There are other answers to that - find a different contract or way of working, reduced hours, etc. But the answer isn't to double time with full time parenting during working hours.
Finally, and just as importantly, when consultants are in the office, you don't want the place feeling like a soulless desert. Again, this will undermine a team culture and a feeling of belonging. So it actually helps a lot to have office staff there when consultants are in, not only so they can sort our that long-standing expenses query, but so they can be in a place where there is banter and life. All of which is a part of the company that employs them.