Do I need an undercoat or primer if painting over a satin painted wall?

[GoldenRuby]

I am about to decorate a fairly dark landing in my house. The walls are currently painted in a slightly shiny/satin deep cream paint, and I want to go for a matt off white (probably Dulux Timeless). Can I just paint it over the existing walls or do I need some kind of primer or undercoat given that the current surface is a bit shiny? Many thanks in advance for any good tips!

You can rub it down to give it a key and/or use an adhesion primer. I use Zinsser 123 water based. You might want to rub it down a bit first but if you use the Zinsser you won’t need to worry about doing a perfect job. It is very quick - recoatable after an hour. I’d then either undercoat or use bog standard matt white emulsion as undercoat before using my actual paint.

I’m not a professional, but I’ve painted a lot of ‘problem surfaces’ and Zinsser products are worth every penny in my opinion. don’t forget, an adhesion primer will stick to everything, so you have to be extra careful not to let your brush, roller etc get at all dry, as you’ll have trouble cleaning them.

Thank you!

Came to say the same as @SisterTeatime - give it a rough sand, Zinsser undercoat and then go for the colour you want. This worked in an old bathroom I had which was really shiny paint.