Loft insulation, and ventalation

[BrianMa]

I'm in process of insulation may loft and have a couple concerns. There is a ceiling vent in each bedroom, and looking as the vent from the loft side I think originally there would have been a crude wooden duct to connect this to the soffit, the picture shows one horizontal board and there are nails where the other would have been.

I'm thinking is this should be sealed up as I really don't want warm house air venting up into a cold loft! But I don't want to seal up a vent without checking. The sofits that these ducts go to seem to be the only ones in my roof that are vented, the others do not seem to have vents.

My loft had zero insulation before and there was no condensation issues, I'm in process of putting in 300mm, sealing up down lighters and getting a better seal around the hatch.

Should I seal this vent?
Should I be concerned that only 2 sofits have vents out of 26?

 

[Burnerman]

Ventilated soffits are a good idea, gales in the bedrooms are not!
I'd lose this vent, insulate your ceilings thoroughly but keep the material away from the under felt.
Soffit ventilation is comparatively new - but thoroughly beneficial should any water get in there. I've helped mine - hopefully - by drilling 3" holes and covering them with a purpose made grille to keep the bugs out.
John