The X Factor mogul and his trusty sidekick were snapped heading into the luxury home on Tuesday afternoon (7 October).
For Simon, it was a day of work on his 55th birthday.
Well, we suppose you don't get to be a multi-millionaire music mogul businessman by taking time off.. although you think he might have made an exception on his birthday!
Simon is mentoring The Overs during this series of X Factor and was previously joined by Sinitta at his home in Los Angeles to whittle them down to the final three he's bringing to live shows.
He chose Fleur East, Ben Haenow and Jay James.
All the finalists will perform live for the first time this weekend, when the X Factor series eleven live shows kick off on ITV1.
No doubt Simon and Sinitta were imparting some advice on their contestants, perhaps finalising song choices?
Simon was clutching a bottle of Lucozade as he exited his car today. Maybe a little too much fun at last night's star-studded Pride of Britain Awards?!
Dad-of-one Simon attended the glitzy ceremony with girlfriend Lauren Silverman, joining the X Factor team on stage to present a 'Child of Courage Award'.
X Factor continues Saturday night on ITV.