Maybe he could only stay an hour or so each time because there were no bathroom facilities for him to use.
His original estimate a red flag for me as the other two were so close to each other. How could he have expected to come in £1000 cheaper?
Why did you choose the cheapest? Really, why? Who recommended him? If he was 60% of the next quote, didn't you wonder how?
Any amount significantly over the estimate must be accompanied but an itemised or broken down costing for the overspend. If you're happy with the job, I might pay what was estimated and say you'll consider the additional costs upon receipt of a receipt for the remainder with these additional costs broken down.
Why not. ? It is not inconceivable that the two others were not particularly bothered about the job so put in inflated prices. It is something I never do , as it is unprofessional and just marks you out as expensive - but there are plenty of guys here that have bragged about making a killing in this way. Obe can only go on gut feelings and recommendations. Also, ask a couple of questions without offending them and gauge their reactions- there demeanour may mark them as someone with whom you can expect trouble
One thing to ask is when he was recommended did the people say anything about how he charged them. May have put in low estimate, but again costs went up but as he had done a good job…
Was the property empty at the time and was the agreement that I could pop in whenever he had some free time to fit it in around other jobs?