Cold calling, possibly a scam
A chap claiming to be from Dyson Energy Services visited to ask if we wanted cavity wall insulation, as it didn't look like we already had it, and it would be funded by the government. He could arrange for an inspection tomorrow as they had surveyors in the area - but only tomorrow. He wouldn't leave a card or any paperwork explaining the funding scheme. The whole thing felt dodgy and had hallmarks of a scam (cold call, pressured to act immediately, only available for short period, wouldn't leave any paperwork) so I said we were not interested. His whole approach seemed very unprofessional, and untrustworthy. I'd expect better from a reputable firm.