Primer for walls with 2 colours on them

[sweetpickle2]

Stupid question alert!

Have recently moved into a house with two colours on the bedroom walls- dark blue on the ceiling/halfway down, and white underneath.

Its not my style so I want to repaint, but will I have to prime so that the colour going on is even, or will it not matter?

You don't have to but if you don't you'll probably need several coats of paint.
I didn't, and it's not a stupid question.

Use cheap white emulsion or grey on the dark blue to neutralise and spend money on trade paint for your choice of colour.

I had some dark color walls and I used multiple layers of paint for them. I smartened up at the end and used B.I.N primer and it went much better after that

Zinsser bin.