A box of old yoghurt pots and coffee jar lids com in handy for all sorts from sticking under the feet of antique furniture to taping over sprinklers.
A water freezer , because most customers idea of a " serviceable out door mains water supply " is one that turns in alright but will not then turn off.
Similarly a plug in three light mains /earth tester.
A set of dental probes.
A long flexible grab it device.
For some EOT , especially in some areas and also in cases where there is a dispute, or a "former" squat and especially places used as a home from home by " ladies of negotiable morals"----my best mate------ a feisty looking Staffy cross. ( also useful in the vicinity of four legged rats)
The list is endless really.
On Pet cleaning a little uv torch and a red photo filter can often find places , where the owners swear blind the animal never goes.
I dont have the nerve to emulate a mate of mine, since retired, who had a call out plumbing firm and carried a specially printed card, which in half a dozen of the more exotic foreign languages, pointed out that customers, who despite agreeing before the work no found they were were unable to pay, or understand ; could apply for a credit account with an associate firm , sadly at a high rate of interest, plus a £20 service charge, and featuring a personal collection( during opening hours)