The 'Arthur' actor was seen getting intimate with the BAFTA-winning actress, famous for her roles in 'Two Pints of Lager and a Packet of Crisps', 'Gavin & Stacey' and 'Benidorm'.
Sheridan had been in the audience at the show, and was also been spotted hanging out with Brand at a food festival last week, reported Sun Online.
On the night of his show, she wrote on Twitter, "Just had dinner with lovely friends. And yes they're wrong yet again. He's one of my best mates (sic)."
Brand, who got divorced from singer Katy Perry last year, followed her a short time later.
Despite them kissing, Sheridan denies she and Brand are dating.