All eyes in the United Kingdom are on St. Mary's Hospital as Duchess of Cambridge's presumed due date looms and people wait for the imminent arrival of a new royal baby.

The Royal Family has refused to comment on the exact date, but that hasn't stopped fans from gathering outside the hospital to await the birth of the baby who will become the third in line to the British throne.

The arrival of the first baby of the Duke and Duchess of Cambridge, Prince William and Princess Catherine, is a hot gossip among fellow mums to be who are due at around the same time.

"The girls who are due around now, we all, we have a bit of a joke about you know, you and Kate could be friends and go on play dates in Kensington Palace gardens," said Sarah Lorenzen, a pregnancy keep fit instructor.

With the next generation of the House of Windsor set to arrive, shopkeepers have tuned up for a brief retail baby boom.

Academics estimate that the royal baby could bring a half a billion US dollar boost to the UK economy through celebrations and sales of royal baby-themed merchandise.

"We can expect people to be buying the royal bib and buying all sorts of things that are themed with the name of the new baby or the color of the new baby," said Professor Joshua Bamfield of the Centre for Retail Research.

The betting fraternity has also been cashing in on speculation over both the gender and name of the new baby, with Diana or Elizabeth among the favorites for a girl and George for a boy.

Inevitably, there are a lot of unknowns surrounding the imminent happy event but, as people enjoy the British summer sun, something of a carnival atmosphere has been created.