Does this roofing quote sound reasonable?

itm2

Just to follow up on this...we went ahead with the job, mainly because three tiles had already fallen off (one from the top row and two from the bottom), and a couple of others on the bottom row had been hit and looked loose. The guy also quoted £2,200 +VAT to do the same job on a smaller section of similar tiling to the left of the window. This estimate excluded the cost of the scaffolding, which was already there.
I decided to get a couple of other quotes for the smaller job. They both came in at £1.500+VAT - including the cost of the scaffolding. So we're getting this done next week by the other roofer.
The original roofer certainly knew what he was doing. We originally asked for a quote (on Checkatrade), asking for someone who could replace the missing tiles and reinstate the section of guttering underneath, which had been dislodged. We also said we were looking for someone who didn't require scaffolding. We sent this guy a close-up photo of the damage, and he quoted us £440 to do the job. He then turned up with a ladder and had a good look at the area. He said that the top wooden batten that the tiles were screwed into was rotting, and needed replacing. He also said that this would require scaffolding. So the quote went up to >£2,000 (£1,200 of which was scaffolding). We reluctantly agreed. 
Shortly after the scaffolding went up he knocked on the door and....guess what...things were worse than he thought, and the whole of that area needed to be redone (new wooden battens and lining for the whole area ) - the new quote was >£4,300 (almost 10 times the original quote). At this stage he had only removed the tiles from the top row, so had no visibility of the rest of the area, although the lower section was already partly exposed due to the two tiles which had fallen off, He also scouted out other potential work on the main part of the roof (which we hadn't asked him to do). and told us that that needed fixing too.
I reckon if he'd conducted a thorough and honest site survey when he first looked at it (on the ladder) he should have been able to give us an accurate quote for the job at that stage, which at >£4k we would not have accepted without a second opinion. The fact that he waited for the scaffolding to go up before doubling the quote was, in my view, pretty disingenuous. At that stage he had only removed one row of tiles, so would not have seen much more than when he first inspected it (with 3 tiles missing).