British bookmakers on Saturday halved the odds on Prince William getting engaged this year to girlfriend Kate Middleton now their on-off relationship looks to be very much back on course.

Celebrity-obsessed tabloids were awash in heavy-handed puns after the second-in-line to the throne appeared in public with Middleton on Friday when he was awarded his wings by his father, Prince Charles, after training with the Royal Air Force.

"Royal Heir Force" proclaimed The Daily Mirror. "The Wing and I" declared The Sun over its banner headline.

William broke up with his long-time girlfriend in April last year but they now appear to be firmly back together, sparking feverish speculation among royal watchers over the eldest son of the late Princess Diana.

Their appearance together prompted bookmakers William Hill to cut their odds on a 2008 engagement from 2-1 to evens.

"Surely it is a case of when not if they get engaged," said Hill's spokesman Rupert Adams.

Middleton, who filed a harassment complaint last year with Britain's press watchdog after being constantly pursued by paparazzi, looked at ease and relaxed in her carefully staged appearance with William on Friday.

The eldest child of middle-class entrepreneurs, Middleton and William shared a house when students at St Andrews University in Scotland.

From there, romance blossomed and she is widely credited with persuading the prince to stay on and complete his studies.

The royal family had very much accepted her in the inner circle of what they call "The Firm." Now she is once more back in the fold.

Kate's parents Michael and Carole became millionaires running Party Pieces, a mail order firm supplying party accessories.