Prince William and Duchess of Cambridge Catherine Middleton are preparing to move to Kensington Palace.

The future king tied the knot with his fiance Catherine Middleton at Westminster Abbey in London in April last year. The royal couple are reportedly interested in expanding their brood soon.

Catherine and her husband are currently based in Anglesey, Wales. Should Prince William not go on a Royal Air Force tour this year, the pair are said to be planning a move to London soon.

"They'll want the extra space and security [if they have a baby]," a source told Us Weekly magazine. "This is why William has chosen not to share his future RAF work plans until next summer. If they're expecting, it will be full-time London for them."

Catherine is excited about designing their wing, which is an apartment that was once inhabited by Princess Margaret, Countess of Snowdon.

"She's keen to work with interior designer Kelly Hoppen, but she wants to do a lot herself," the source revealed.

The pair are rumoured to be actively trying to have a baby and are expected to reveal the news when Catherine is three months pregnant.

"The pregnancy will be announced," the source said. "It won't be hidden."