Simon Cowell will begin filming for 'The X Factor' tomorrow (08.07.15).

Simon Cowell

Simon Cowell

The music mogul delayed the beginning of the show on Monday (06.07.15) following the death of his 89-year-old mother Julie, although he has now agreed to return to the competition after having two days off to grieve.

A source close to the judge told the Daily Mirror newspaper: "Simon needs time to get over her death. But he knows how many people are involved in 'The X Factor' and doesn't like to let them down.

"Julie was a big fan, so it feels right to take some time out and then work on the show."

Extra audition sessions will also be held on Thursday (09.07.15) in Manchester, where the 55-year-old star will make up for lost time alongside fellow judges Nick Grimshaw, Rita Ora and Cheryl Fernandez-Versini.

Announcing Julie's death on Sunday evening (05.07.15), the family said they were heartbroken and would "miss her terribly".

A statement read: "Today our beloved mum Julie passed away. Anyone who had met her would know what a truly special and kind lady she was. We are heartbroken and will miss her terribly, but she is now at peace."

A spokesman for the family said: "We would like to thank the media for kindly respecting Julie's privacy throughout and we politely request continued privacy for the entire family at this particularly difficult time."