It is a perfect example (ok maybe fairly extreme granted), of exactly what can happen, the freeholder can suddenly drop things on you like this at any time as the land is theirs!!!
You say he's just been unlucky, yes true he has but at the same time, if he had purchased a freehold property that would definitely not come up!
We had similar issues in the flat we used to live in, 4 days before christmas one year we got a letter through informing us of intended works to the roof, as it was only a block of four flats and we were first floor, we didn't know if the cost would be shared with all four flats or just the two it affected, the total cost was estimated at £10,000 meaning we would have to find either £2,500 or potentially £5,000 if the work went ahead!!!
Was a hell of a shock and the timing was awful as the office was shut for xmas so we had two weeks of not knowing and stress before we could even talk to anyone about it!!!
As luck would have it the economic downturn meant such projects were shelved and it never happened but the potential being there for it is horrible!!!