What can I use to fill this gap?

[SuePerkins]

Recently moved house. Have found that there is a draught coming in through a gap under the kitchen cupboards which are on an outside wall with an air grate in it. There is a 1cm ish gap between the underside of the cupboard and the top of the kickboard. Any ideas?

Stick on draft excluder?

The proper way would be to remove the cupboard, it might even unhook if it's a top cupboard (2 person job)
Then what I did in that situation was remove the grille, put a couple of bricks in the hole, and then plaster over it.
However you could just get a bit of hard board or even cardboard and gaffer tape it over!

I never got to the simple way that may just redirect the draught elsewhere - basically just get some flexible sealant and put plenty around the edges where the draught comes