That looks great Paul! Is it a beehive?
Bruno is looking more and more like he's moving in to your heart, if not quite yet into your home. The flea treatment wil have worked by now so it will be safe to bring him indoors when you're ready.
The vet not co-operating? Meaning they're gonna charge you for the check-up? If he is microchipped, they are obliged to report him to the microchip company and allow for the owner to be tracked down. Be ready for this, OK?
I've looked on the National Pet register for your general area and no-one has reported him missing. I'll check the other sites too for you as I'm a member on most of them. If there is no chip present, and you've advertised him locally for seven days, then you can take ownership of him as a stray.
Ask the vet if they participate in the RSPCA's C4 scheme which helps with neutering the stray population (unless he's already neutered?) and how to get a voucher in your area. Usually Cats Protection League will help out with vouchers for neutering strays so the vet should not charge you for his operation if he participates.