'Suits' cast. Picture: Instagram

Meghan Markle's 'Suits' co-stars are in London to attend the former actress' wedding to Britain's Prince Harry on Saturday.

On Friday evening, Meghan's on-screen love interest, Patrick J Adams, took to Instagram to share a snap of the cast sharing a 'last supper' before the royal wedding. 

The last supper #royalwedding

A post shared by Patrick Adams (@halfadams) on

Meghan, however, was not in attendance as she spent the eve of her wedding with her mother, Doria Markle, at Cliveden House, about 11km away from Windsor.

Adams also tweeted that he'd just learnt that 70 years ago his grandparents were married in a small service in Windsor.

During an appearance on the 'Today' show in the US on Friday, Gina Torres, Sarah Rafferty and Rick Hoffman said they're excited to bear witness to the royal wedding.

Sarah - who played Donna Roberta Paulsen in the legal drama - said: "They're a great match."

And asked if they expected to be on the guest list, Gina (Jessica Pearson) said: "I was. I think you know, you hope, and I hope nothing but the best - as we all do - for her, this is an incredible step in her life, so to bear witness to that is extraordinary."

Rick (Louis Litt) claims he was the first person the former actress told about their romance and he couldn't believe she was going to join the royal family.

Asked about his reaction, he said: "I was like, 'You've got to be kidding me.' It was like both of us in the trailer, like, 'You're dating a prince.' "

The 47-year-old star said he was sure to advise Meghan not to rush into things and not to get "hurt". 

He added: "I was like, 'Take it slow, be careful, don't let him hurt you.' "

Gina added that whilst the couple had to keep their relationship under wraps for some time, because "there was reason to keep [the romance] close to the vest", she could tell how "excited" Meghan was.

Sarah added that the whole 'Suits' cast were like sisters on the show and said the fact they are going to the wedding makes it even more a "family affair". 

She said: "We called ourselves the sister wives ... We were with each other for longer than we went to college or high school with our friends.

"So we became family. We're still family, so this is a wonderful family affair."