The property next door to us was recently rented by a young couple (early to mid twenties) Prior to that it has been vacant since we bought our house in September. (In fact it was on the market at the same time as our one was) We met them when they were moving their stuff in so they know we have a baby.
10 days ago was the first night they slept there and they woke DS (7 months) up at midnight by clattering around in their shed which is practically below his window.
The next night they were again being noisy and woke the baby and DH went over at 11pm and asked them (politely) to keep the noise down. Turns out they were assembling some bunk beds. 
The houses basically mirror each other so all the bedrooms back onto each other and the sound carries.
A few days after that they clunking around again late but luckily didn't wake the baby. And again tonight there's been banging and now DS is seriously wiggling.
DS is normally a really good sleeper but two weeks ago I had to get him up late at night as DH had cut his finger badly and I drove him to A&E. DS then got into a bad sleep pattern which I was trying hard to overcome but when the neighbours banged in the shed, it just cemented the problem. Once DS is up he thinks he's been to sleep all night and is then up and unsettled for hours. And he was doing this every night.
DS has JUST about got settled into a sensible sleep pattern again and I really don't want to undo everything I've worked so hard for.
I understand that having moved in recently they will have things to do, and I would never expect them to be quiet during the day, even if it was during DS nap time as obviously his schedule is nothing to do with them. But I think late at night is a different matter. DH also works in care so has really early starts, so it's not fair on him either.
AIBU to think I shouldn't have to keep reminding the neighbours to keep the noise down?