19 February 1913.
Inspector Riley of the Metropolitan Police Special Branch and Major Cooper Keys, the Chief of the Explosives Branch of the Home Office, were notified by Superintendent Coleman, the local man, about the explosion. A motor car P8487 [LF4587] was traced passing through Banstead at 2.50 am and returned at about 5am. The car was heard to leave the vicinity of the house at about 4.30am and so the fuse must have taken about 2 hours to burn down.
An earlier arrest of Mrs Pankhurst
On 24 February Mrs Pankhurst was arrested in London for the bombing and later taken to Leatherhead Police Station where she was questioned and charged. Superintendent Coleman reported:'She is being detained in Inspector Tudgay's sitting room and I have arranged with the Inspector to sleep her in one of his bedrooms tonight.'The Director of Public Prosecutions had instructed that whilst in custody, Mrs Pankhurst should be treated with due consideration! Next day she was bailed from Epsom Magistrates' Court, having been driven to the court with the Superintendent. This made her the first person in the Surrey Constabulary area to have been "conveyed to court in a motor car."
7 March 1913 C.I.D New Scotland Yard.
Referring to the recent outrages by the Suffragettes in the Metropolitan District and at Walton-on-the-Hill, I beg to report that at 3.25pm on the 19th February last, a telephone message was received from Superintendent Coleman, Surrey Constabulary, Dorking, stating that at 6.10am that day an explosion had occurred at Sir George Riddell's house at Walton-on-the-Hill and that a tin of unexploded black gunpowder had been found in the house.
The explosion is supposed to have been caused by a five pound tin of coarse grained gunpowder which had been placed in a bedroom on the first floor. The room in which the explosion took place was wrecked in the interior and the western wall was bulging about four inches. Inquiries have been made regarding the outrage and the movements of car LF4587 [P8487] on the 18th and 19th February and in consequence of Mrs. Pankhurst's public uttering regarding this and other outrages, the Director of Public Prosecutions has decided to take proceedings against her under the Malicious Damages Act 1861.