Thames Valley police say two men aged 34 and 35 and woman aged 36 are in custody
Three people have been arrested in connection with a burglary at Blenheim Palace in which a gold toilet was stolen.
Thames Valley police were called to reports of a burglary at Winston Churchills birthplace in Woodstock, Oxfordshire, on 14 September.
The lavatory, an art installation valued at about 4.8m, was allegedly taken in an overnight raid at the 18th-century estate.
On Wednesday, police announced they had made three further arrests in connection with the burglary.
A 35-year-old man, a 34-year-old man and a 36-year-old woman, all from Oxford, were arrested on suspicion of conspiring to commit a burglary other than a dwelling. They all remain in police custody, a spokesman for the force said.
The toilet, named America, had been connected to the water supply for visitors to use in a wood-panelled room.
A 66-year-old man from Evesham was previously arrested on suspicion of burglary and a 35-year-old man from Cheltenham was arrested on suspicion of conspiracy to burgle.