EDEN CONFIDENTIAL: Did 15-year-old Duke have secret daughter... with his half-sister?

He owns more than 200,000 acres and four ancestral seats, three in Scotland and the fourth, Boughton House — 'the English Versailles' — in Northamptonshire. 

But does Richard Montagu Douglas Scott, 10th Duke of Buccleuch, also have family skeletons rattling around in the proverbial cupboard?

I ask because of the claims being made by Robert Calder, a 64-year-old asphalter from Kettering.

Though originally from Scotland, Calder would appear to have little in common with Buccleuch, 70.

But that, Calder says, fails to take into account a love affair in the 1930s — between his grandmother, a maid in domestic service, and Johnny, the Earl of Dalkeith.

The latter became the 9th Duke of Buccleuch, having married in 1953 and had four children, the eldest being the current Duke.

He had had another child years earlier, says Calder. 'My grandmother had a daughter in 1939,' Calder tells me. 'My mother.'

The baby's father couldn't be named on the birth certificate — and not just because the parents were unmarried. '[Johnny Dalkeith] was not quite 16 when my mother was born,' explains Calder.

His mother, he adds, died aged only 43 in 1983. Calder hitchhiked from London to Edinburgh for the funeral, only arriving as the service ended. 

'There was a man in a wheelchair, with a grey blanket or shawl over his knees,' he remembers. 'He smiled at me but we didn't speak.'

Later that year, an acquaintance who'd done work on the Duke's Boughton estate said that the aristocrat would like to see him. Calder wasn't interested.

'I'd never heard of the Duke of Buccleuch and I didn't know he was in a wheelchair,' he recalls.

Years later he learned that the Duke had been in wheelchair since a hunting accident in 1971. He heard many cryptic comments. 

'I was told: 'It's not who your father is that's the problem — it's who your mother's father was'.'

In the last two years, he has renewed his efforts to unearth more — and has asked the current Duke what, if anything, he knows, but with no reply.

Perhaps that's because of Calder's other extraordinary claim. The 9th Duke and Calder's grandmother were, he says, more than lovers, thanks to what had happened in the previous generation.

'They didn't know it – couldn't have known it — but they were half-brother and sister.'

DNA testing would surely sort truth from myth. It may, though, be tricky to arrange. 

A spokesman tells me that the Duke 'could not be reached for comment'.