Former computer software engineer Ian Stewart alerted police to him being in possession of ‘missing’ Helen Bailey’s phone after he failed to anticipate the device would be picked up on the WiFi network at their Kent holiday home, St Albans Crown Court heard yesterday.

Described by prosecutor Stuart Trimmer QC as a ‘very significant event’, the phone was picked up when Mr Stewart went to the home a day after he reported Ms Bailey missing on April 15 – four days after she was killed and dumped in a cesspit along with her dog Boris.

Contacting the police and going to the home in Broadstairs was a result of the pressure mounted on Mr Stewart by her family who were becoming increasingly concerned for her whereabouts, the jury heard.

On April 21 an officer went to the home to examine the wireless router which established that the phone had connected to the router.

“The property had an active WiFi network and Helen Bailey’s iPhone came in range of the WiFi and connected to the network, so he must’ve been in possession of her mobile phone at the time,” Mr Trimmer said.

On June 7 another officer went to the home and found the router had been removed. It was later found packed away at their property in Royston.

Mr Stewart – who is originally from Letchworth – and Ms Bailey both used their phones and social media regularly. The last email Ms Bailey sent was from her iPad at 10.51am on April 11, shortly before she died.

When reporting the disappearance, Mr Stewart had said her best friends had not heard from her – which Mr Trimmer said was to imply she had the phone.

Mr Stewart refused to give his own phone to the police, saying that if Helen was going to contact him she would do so on his phone. He said he had lost his phone in Cambridge, and her phone was never recovered.

The court also heard how Mr Stewart had access to the successful author’s bank account and emails and in the afternoon of the alleged murder, he changed a regular standing order of £600 from her to him to £4,000. He had deleted internet history but this was found in a fragment of data uncovered by police. Ms Bailey was an avid Arsenal supporter, she reguarly attended matches at the Emirates stadium and had been a season ticket holder for a number of years. In the period she was ‘missing’, Mr Stewart renewed their Arsenal season tickets costing £1,577.49 each with money from their joint bank account after she was sent an email from the club on May 12 to her personal account saying the current tickets were due to expire.

When checks were made on electronic devices at the house, Mr Stewart’s behaviour was said to be ‘unusual and strange’ as though he didn’t expect such a full search to be conducted.

The trial, expected to last six weeks, continues.