Kate and the Queen's Adventures on the London Tube.

Well, Catherine hopped right back on the public transport system today when she made an official visit to Baker Street Underground Station with Queen Elizabeth II and Prince Philip. The funny thing is that she reportedly requested to go and seemed to enjoy herself while at the event honoring the London Underground's 150th anniversary.

"I used to use the Tube on a regular basis," Kate said. "I miss traveling on the Tube."

Of course, since this was a royal engagement, the duchess certainly wasn't rubbing elbows with local commuters (remember when Prince Charles and Camilla took the train for a single stop?). But the expecting royal was even presented with a Baby On Board badge, which *real* pregnant women get when they travel on the Tube, by the London Underground staff. Rather than pinning it on her teal Malene Birger coat, Kate politely replied, "I'll make sure I wear it at home."

It was also nice to see the Queen out and about after her recent bout of illness (she's been forced to cancel many engagements). For her royal ride, the monarch went with a cream Karl Ludwig dress and coat and an Angela Kelly hat. Looking lovely, ladies!

The expectant duchess gets pinned down with a "Baby on Board" button, given to pregnant riders so fellow passengers will know to offer up their seats. The Daily Mail reported Kate as telling the queen, "I will have to wear it at home!"

The Duchess of Cambridge, arrives by separate car, to join Queen Elizabeth II and the Duke of Edinburgh, at Baker Street Underground station in London for an event celebrating the 150th anniversary of the Tube.