How much notice needed for DS to resign?

[Muddle2000]

He has been in the hotel industry for a few years. 4 months ago he landed a new job in a deluxe hotel. However after 2 months they started mucking about with his shifts. They said it was just a temporary thing to help out but now it looks like they were lying about this.
He has complained politely about this and got nowhere. He says they are always trying to undermine him.
He has now got another job . He is paid monthly but thinks as he is leaving within the 6 months probation period he only has to give a week's
notice. I presume that is in his contract.
The new job starts in a month so I do not want him to lose out.

I'm not sure I understand you. Does he just "think" he has to give a week's notice or does it actually say that in his contract?

If his contract doesn't specify notice, it will be a week. If it does specify, it will be whatever it says.

He needs to check his contract. What does that say about notice periods?

It depends - if he has a contract, the notice period will be set out in this. However if there is no contract, he has to give one weeks notice for every year he worked there (so one weeks notice if he has only worked there 2 months)

"However if there is no contract, he has to give one weeks notice for every year he worked there"

No he doesn't. Statutory notice for employees is a week after working one month, in the absence of a contract requiring more.

Thanks I stupidly thought as he was paid monthly it would be a month's notice (statutory) Yes I will ask him to check his contract
He starts the new job on 3rd October and I just do not want him to lose
out . They are a bunch of liars so I would not trust them.
Loads of people have left/ are leaving at the moment .
Funny that..

I found that in the company I work for the 1 week notice is only on the companies side - is if they decide to let you go in the probation period it can be a week. But on the employees side it's the usual notice period - so whatever it says in his contract. Most companies will negotiate - if they are sensible.