Police believe the head is that of Julia Martha Thomas, a widow in her fifties who was killed by her maid.
In a case known as the Barnes Mystery, 29-year-old Kate Webster murdered her employer with an axe after she returned home from church on a Sunday evening.
Webster, a convicted thief and fraudster, dismembered the body, threw parts of it in the Thames and disposed of the rest in various places around London.
The case attracted great publicity. Webster was tried and executed for the murder – but Mrs Thomas’s severed head was never found.
The skull, which was unearthed on Friday, has yet to be properly examined by specialists but police say they are almost certain it is that of Mrs Thomas.
The murder victim lived at almost exactly the same spot as Sir David, on a road in Richmond, south-west London.