John wrote:

Before I pay said man £50(?) to do this is there
any point in me buying these foam or powder destroyers that are available.

Yes. Nippon ant / crawling insect powder. £3 from morrisons. Sprinkle
liberally on the air brick. They will be gone in three days.

Google back for the thread in uk.d-i-y "Wasps nest under floor" on the
3rd July.

--
Adrian C