THERE'S a buzz in the air in York city centre as film crews prepare for a top secret project. 

Past the bustling scenes at York Food Festival and the usual queues outside Bettys Tea Rooms, tour guides are telling excited tourists about the city's past cameos in film and TV.

"We have been expecting some filming in the next week or two, so this must be it," one tour guide tells his group.

"Sometimes they keep it quiet."

The filming is taking place at York's Mansion House over the next two days while the former Post Office in Lendal appears to be in use too.

York Press: Pictured left, the old Post Office in Lendal. Right, Mansion House is a topic of discussion with today's tourists.Pictured left, the old Post Office in Lendal. Right, Mansion House is a topic of discussion with today's tourists.

One member of the film set - dressed in a blue jacket - is guarding the entrance as boxes are unloaded and taken inside.

Read more: Film crews set up in York city centre

Film and TV lighting company PKE Lighting - which has helped bring productions like Broadchurch, Sherlock and Dr Who to life - are parked up in St Helen's Square.

York Press: The PKE Lighting van seen outside the old Post Office. The PKE Lighting van seen outside the old Post Office.

But anyone looking to spot the stars today might be disappointed with extras expected to be the only cast members on set today.

The Press understands the filming is for upcoming ITV period drama.

It marks another moment in the spotlight for Mansion House - one of several buildings used in filming for ITV's Victoria, historical television drama series featuring former Dr Who star Jenna Coleman.

Read similar articles: Stars turn out for filming in York city centre

York Press: Passers-by stop to see what is happening in St Helen's Square. Photos by Natasha Meek.Passers-by stop to see what is happening in St Helen's Square. Photos by Natasha Meek.

Built in 1732 for the Lord Mayor of York, Mansion House was once the thriving heart of York society and it’s a masterpiece of 18th-century architecture from head to toe.