Kate Beckinsale posts topless photo to Instagram

Kate Beckinsale attends the 2019 Vanity Fair Oscar Party. Photo / Getty

British bombshell Kate Beckinsale has shared a saucy photo to Instagram alongside a bizarre caption that questions the very nature of our existence - and the correct way to prepare a cheese toastie.

The 46-year-old actress shared the photo on Friday, posing topless wearing lacy underwear and preserving her modesty with her hands.

The black and white photo shows Beckinsale gracefully reclining as two men work to style her hair and do her makeup.

She wrote: "Chase feels there's a very good argument using anthropic reasoning to suggest we are living in a simulation," referencing makeup artist Chase Aston and his theory that the entirety of human existence lies within a complex simulation.

She adds: "Italo says there's no proof that it's physically even feasible for a posthuman civilization to create such a simulation," about stylist Italo Gregorio.

Beckinsale then adds her own down-to-earth take on the weighty conversation: "I can't fathom why anyone would put tomato in a cheese toastie."

Actress Jaime Winstone commented: "Whatever it is you're talking about, I like it!!!"

A fan wrote: "You are amazing in every possible way," while another went further to say "HAIR TO TOES AMAZING."

Last week was a tough one for Beckinsale who was forced to evacuate her home after California wildfires raged around the property.

View this post on Instagram

We are safe. Thank you so much to everyone who checked in. Sending love and hope to everyone else who walked out of their house at 3 am to this, love and admiration to the @losangelesfiredepartment and most of all to David and Dorothy who didn’t need to remember in the middle of the night that I can’t drive but did. And to everyone who has offered me a place to stay despite my rolling with four animals including an epileptic cat. Angel people . So grateful x

A post shared by Kate Beckinsale (@katebeckinsale) on Oct 28, 2019 at 6:38pm PDT

She revealed she had escaped the fire thanks to her neighbours, who remembered that she can't drive and evacuated her and her four pets, including an epileptic cat.

The star also praised the Los Angeles Fire Department, saying they had "love and admiration" for their efforts in fighting the fire.