Simon Cowell's security guard has rejected any suggestion an almost £1 million raid at the property was "an inside job".
He admitted he must have been in the toilet when a burglar broke in to steal jewellery and passports from an open safe.
The X Factor supremo was asleep in the five-bed house in the well-to-do area of Holland Park in west London, as were his partner Lauren Silverman, their toddler son Eric, and the child's nanny.
Darren February, 34, is accused of climbing over walls and getting in to the house, where Cowell has lived for 10 years, through a patio door.
Simon Williams, Cowell's private security guard, had been downstairs in his office at the four-floor house at the time the entertainment boss went to bed at around 12.30am.
About an hour later Mr Williams heard a loud noise, and checked a gym, kitchen and guest room in the basement.
He discovered the patio doors on the ground floor were open and a handbag and laptops on a coffee table outside.
Asked if he was surprised to see those items outside at such an early hour of the morning, he told the court: "Surprised? Possibly. Confused, to be fair."
A police officer who arrived at the scene said Mr Williams told him Cowell and Ms Silverman may have "had an argument" earlier that night, at which point the laptops were left outside on the coffee table.
Police Constable Tze Chua said Mr Williams "appeared very reluctant to let me in" when police asked to check inside the property.
Mr Williams told the court: "It's always been protocol that the house owner did not want police on site, unless there was something extreme and there was an important reason to be there."
The burglar was spotted making off by security worker M'Batonha Mendes, who was patrolling the scene overnight and has identified him as being the defendant, the jury has been told.
Giving evidence, Mr Mendes said he spoke to Mr Williams after collecting a passport and items of jewellery dropped by the burglar.
He told the court: "He (Mr Williams) said he went to the toilet and when he came out he noticed that the front door was wide open and all the lights were switched on in the house."
Mr Williams said he was the only staff member awake in the house at the time of the burglary, and had not seen the man making his way in to the house on the CCTV cameras monitoring the outside of the property.
He accepted he would have been either in the kitchen making a hot drink or in the toilet.
He added: "I'm assuming it would've been the latter."
Giles Newell, defending, put it to Mr Williams that Mr Cowell had told the media after the burglary that he suspected it was "an inside job".
He asked: "Do you know anything about this being an inside job?"
Mr Williams replied: "No, I certainly do not."
February, who has committed 37 burglaries, many of which took place in that area of the capital, was not in the dock at Isleworth Crown Court for the second day of his trial.
Judge Martin Edmunds QC told the jury the defendant had chosen not to attend court, and said there was no medical reason for his absence on Thursday, but asked them not to speculate as to why he was not there.
The items stolen during the burglary on December 4 2015 included a diamond ring, bracelet and watches amounting to the value of around £950,000, as well as two passports.
The safe had been left open as Ms Silverman was due to fly abroad that morning and "wanted to quietly get her jewellery", the court heard in a statement read on behalf of Cowell on Wednesday.
He also described the couple's immediate concern for their son, who was unharmed, when they were woken and told of the incident.
Prosecutor Denis Barry said traces of February's DNA were found on gloves discarded on the route the accused is said to have taken as he fled the scene.
The defendant, of no fixed address, denies one count of burglary.
The trial was adjourned to 10am on Friday.