Tony Moore had recorded a surprise video and persuaded bosses at the shopping centre, near Glasgow, to show it on their 23-feet by 13-feet TV screen. And after getting over the surprise of seeing her partner, 43, propose on film, the 26-year-old was quick to say: "Yes."
Mr Moore, from Laurence Drive, Millenium Court, Glasgow told Diane he was going to see a mortgage advisor on Monday.
But instead, he slipped away to the shopping centre with the couple's 14-month-old daughter, Lilly to make the proposal video.
To grab Ms Sheridan's attention, the toddler was seen first in the film with the Michael Bublé love song, Everything, playing as the backing track.
Then Mr Moore came into view, went down on one knee, produced an engagement ring and asked her to marry him.