Conman John 'Goldfinger' Palmer was under surveillance for 16 years

Notorious conman John "Goldfinger" Palmer, who was shot dead last year, had been under surveillance by secret intelligence officers for 16 years, the BBC has learned.

Palmer, who was once described as Britain's richest criminal, was shot dead in the garden of his home in Essex in June 2015.

The operation, codenamed Alpine, had gathered intelligence on Palmer from RAF Spadeadam in Cumbria from 1999.