If a plumber takes up floor-boards to fix a leak, should he fit the floor-boards back after fixing the leak?

I send work out to contractors all day, every day

I expect them to do lift the flooring, the boards, repair the problem & if routine, put the boards & flooring back down.

If that was what he priced for then yes

Why would he not include this work, the job was to find, repair and then leave as found.

When I was working everything would be back to how I had originally found it.

I would never take the money or pay until I'm or the customer was 100% happy

That depends on contract and payment.

You would have to pay him for that job. Generally it would be regarded as part of the job, but if the home owner prefers doing it himself the job would be cheaper.

its standard in the uk for a plumber to replace boards ..if he has removed them ..but as he has normally had to remove the tongue to take up they do not not go back as well as before

Not unless it is specifically implied. His job is to fix whatever that deals with the plumbing, normally they would have discussed options prior to tearing up the wall or floor.

Of course they should be replaced. I always replace them, its all part of the job

depends on what was agreed to pryor to job beginning

Yes, but he will charge for his time