Her mate, Benedict, had disappeared and her cygnets from last year had flown the nest.
Then, at the 11th hour a new male swan arrived on the water.
It was love at first sight and, after just a couple of days the pair have become a couple and have built a nest.
The romance has delighted the manager at the picturesque castle, Sue Ellis, who launched a competition to name Beatrice's new mate.
"This one does not have a leg ring as Benedict had so it is very unlikely to be him," she said.
Last year's cygnets were also given rings before they left the castle moat.
Most swans will mate for life and it is not know what happened to Benedict.
Sue has not spotted a leg ring, so he is unlikely to be her former mate Benedict or one of their cygnets.
An eagle-eyed visitor to the castle noticed the two swans mirroring each other, normally the prelude to mating. The visitor continued filming and moments later, David Attenborough style, caught the mating on camera, followed by the classic paired neck extend by the two birds.
The video can also be seen on the castle's Facebook page Official Whittington Castle.
Last year no fewer than nine cygnets hatched at the castle; a triumph for Beatrice after the heartbreak of the year before when vandals smashed the eggs. CCTV was then installed to ensure any vandalism was caught on camera.
The winner of the competition to find a name for the new male was being announced today .