Didn't Carson tell them the dress code? Downton Abbey stars Michelle Dockery and Laura Carmichael opted for a summer casual look at Elizabeth McGovern's 60th birthday in Mayfair

What would Mr Carson the butler say? Three stars of Downton Abbey at a birthday bash and not an evening dress or tiara in sight!

Instead, Michelle Dockery and Laura Carmichael opted for a summer casual look when they joined Elizabeth McGovern to celebrate her 60th last week at Scott’s in Mayfair.

Once described as Britain’s grandest restaurant, the glitzy seafood eaterie was a perfect setting for the glamorous trio to enjoy a chilled lunch on one of the hottest days of the year.

Michelle, 39, who played Lady Mary Crawley, and Elizabeth, who was Cora Crawley, Countess of Grantham, arrived in a chauffeur-driven limousine. 

Laura Carmichael, 35, who played Lady Edith in Downton Abbey, seen leaving on foot in a cooling black linen dress, sunglasses and sandals 

Michelle Dockery and Elizabeth McGovern leave Scott's in Mayfair after celebrating the latter's 60th birthday 

Laura, 35, who played Lady Edith, arrived on foot in a cooling black linen dress, sunglasses and sandals and carried an elegant bouquet for her co-star. 

After the two-hour lunch Michelle, in a leopard-print sleeveless top, baggy denim trousers and sandals, and Elizabeth, sporting an on-trend grey up-do with a comfy shirt and slacks combo and white trainers, climbed back aboard their limo.

Laura followed with a waiter bringing her a carrier bag. 

It led onlookers to wonder whether the actress had asked for a ‘doggy-bag’, an increasing trend among diners to counter food waste – the current focus of a Mail on Sunday campaign. 

‘I couldn’t tell if it was a doggy-bag or a gift item, but the waiter was happy to help her,’ said a fellow diner. ‘The three of them seemed to have had a great time.’