Seal up redundant warm air heating wall vents?

Hi would it be advisable to seal up air air vents in an outer wall which used to ventilate rooms when hot (blown) air heating was in place?

Now I have storage heating (ex council house).

These air bricks/vents lead outside from (near) roof level in very room.
They have been plaster boarded over on the inside but I am worried these vents will have a negative effect and reduce the effectiveness of the cavity wall insulation.

Any advice welcome

You would be better asking this question on the plumbing and heating page - the vents are likely to be for gas appliances which you may still have and blocking them could be dangerous.

In the 70s my parents had warm air heating and the only vents to outside were to allow the boiler to get air without killing us - not to cool the house.

These vents had nothing to do the warm air heating. They are just to let some natural air in the room.

Removing the input of fresh air/removal of stale air could lead to condensation issues.

Yes, may feel nice an warm, but so will the mould spores