When he didn't show up in London, Mandy deduced his fate, and cried silently in London Market. The Doctor and Amy watched from the TARDIS scanner. Mandy was subsequently followed by Amy, and, when she confronted her, she had to warn Amy not to enter a tent marked "KEEP OUT". During this time, she noted Amy's Scottish accent and informed her that Scotland had wanted their own ship rather than be a part of Starship UK.
Amy ignored her and came back in shock, then was knocked out by the Winders. Mandy waited for her outside the voting booth with the Doctor. When the Doctor pressed the Protest button, Mandy was locked outside, whilst Amy and the Doctor dropped down a chute to the star whale "below".
Queen Elizabeth X approached her in a mask, and Mandy joined her in collecting the Doctor and Amy. She was then taken to the Tower of London, where she was reunited with Timmy. A part of the star whale approached the two children, and was gentle with them. (TV: The Beast Below)