I am with the Co-op too - hate banking there but it is the only one which will pay me (as a member of the FSB) to be a customer. My payments show up on the 4th working day after notification to me i.e. routinely on Thursday (based on looking at relatively few recent transactions.)

I think 2 days is optimistic but my personal bank - Nationwide - does achieve 3 quite often.

when a disbursment would move to the next day

The sarcastic answer would be when the little hand. . . . :-)

But more helpfully, the process starts when you start it and usually ends when the money is credited to your account sometime in the early hours of the morning.

Working days are only relevant in that, dispite the whole process being eletronic, nothing happens on weekends and bank holidays.

Put another way, a disbursment made on Thursday and hitting your account the following Thursday will not have taken, as you can be forgiven for thinking, seven days, but only five working days.