The happy couple, who got engaged a year ago, exchanged vows in front of around a dozen guests, including Keira's mother, Sharman MacDonald, and James' father, Nicholas, and brother, Bill.
In keeping with the low-key tone of the day, Keira wore a Chanel jacket over her strapless white tulle dress, and she adorned her hair with a delicate garland of tiny flowers.
"It was a very moving ceremony," an onlooker tells MailOnline of the thirty-minute affair. "Keira looked extremely moved by the whole thing—there were certainly tears of happiness."
"It was sunny day without a cloud in the sky," continues the witness. "There were cheers of 'Well done, Keira' when she came out, but there were so few people present so they didn't make much noise."
Neither did the compact car—a silver Renault Clio—that whisked the bride and groom away!
"It certainly looked as though it had seen better days," jokes one eyewitness.
"We're not really big-wedding types," Keira told Marie Claire in March. "I could have six fake weddings. God, that would be expensive. I don't need to have all that."
Would you prefer a low-key wedding like Keira or something much bigger? Tell us in the comments section or on Twitter @OKMagazine