Monicker

It's pronounced "Day-th".  The BBC's new HR supremo, Valerie Hughes-D'Aeth, unsurprisingly lists one of her interests as genealogy.

The first Hughes-D'Aeth I can trace was the Reverend Wyndham Charles Hardy Hughes D'Aeth, who graduated from Corpus Christi, Oxford, to the living of St John the Baptist Church in Buckhorn Weston (currently in Dorset) in 1877.  His father was Charles Le Narivel D'Aeth, born in Belgium in 1793.  That suggests the surname is a mangle of someone who came from the municipality of Ath, rather than anything more sinister.

Somewhere in the H-D tree there is Arthur Cloudesley Shovell Hughes D'Aeth, captain of HMS Minotaur in the 1916 Battle of Jutland. More later...