Farrow and Ball

[SReh]

Hi folks.
I have some questions on Farrow and Ball.
Has anyone used the new Dead Flat finish and is this worth the extra money?
We are wishing to apply Brassica (purple shade) to the chimney breast and a wall in the dining room. Neither wall is overly big.
The current wall colour is a plain white. I was told by Farrow and Ball I would need to purchase their dark primer undercoat or else the new Brassica shade won’t look right applied on top of white. Is this correct?
I have very little experience of painting and decorating and appreciate all advice.
Thank you! xo

We've just used it. We went the other way and covered Nearly Black with Strong White. We ignored the advice about primer and just painted it. Took two coats but it's covered it well.

Also used it on the skirting boards and it's fine. Looks good.

I like walls and skirting's same colour and not having to cut in was great.

My bedroom used to be Brassica and we just did two coats over the previously pale blue paint, no primer.