Kate Middleton recycles Zara top for 1st public engagement since Prince George's birth Duchess joined Prince William at start of ultra marathon in Anglesey She wore spotty £38 Zara T-shirt under green Ralph Lauren blazer She was last seen in Zara blouse when five months pregnant £570 Ralph Lauren jacket is another of her wardrobe staples Onlookers said new mother looked 'absolutely gorgeous' Usually when the Duchess of Cambridge steps out in recycled outfits, women across the country look on with admiration and think, "maybe she is like us after all." But after Kate made her first public appearance since giving birth five weeks ago, those approving looks will probably be tinged with a little bit of envy. Yesterday the Duchess, 31, stepped out in a recycled jacket and blouse, and, sensationally, her pre-pregnancy trademark skinny jeans, revealing just how quickly she has managed to snap back into shape. Back to business: Kate in her skinny jeans yesterday. She also wore a £38 blouse from High Street store Zara and a Ralph Lauren blazer she has been pictured in on previous occasions Break from changing nappies: Kate joined Prince William at the start of an ultra marathon in Anglesey As well as the £180 jeans by designer Paige, she wore a £39 sleeveless patterned blouse by Zara - last worn when she was just a few months pregnant - with a £570 Ralph Lauren hacking jacket and her favourite £80 Pied a Terre wedges. The Duchess hadn't planned to step back into action so soon, with her first official engagement not scheduled until September 12. But earlier this week sources indicated that she was considering joining Prince William to officially start a marathon on Anglesey, where the couple have lived for two years. Kate is understood to have been keen to thank locals for their support and discretion before the couple return to London after William's search and rescue RAF posting ends next month. Welcome: The Duchess was given flowers and cards from well-wishers (left). Her trademark skinny jeans and Pied a Terre wedges made an appearance in Canada during the 2011 royal tour (right) Starter's orders: Prince William had been asked to officially start the long distance race High Street fan: Kate's blouse is no longer on sale at Zara. She's often seen in clothes from the store In the end a decision wasn't made until just a few hours before the event yesterday morning, after aides were told that "little rascal" Prince George, as his father likes to call him, had given his parents a relatively peaceful night. While speaking to locals at the event, the Duchess revealed that her mother, Carole - or granny as she called her - had come up to North Wales to babysit. He's doing very well. He's sleeping well but I know these things suddenly change at a minute's notice," she told fellow mother Sarah Bingham, 38. Supporting runners: The couple head to the start of the ultra event that will last three days On the slopes: The Duchess was last seen wearing the Zara top when she was five months pregnant Re-worked outfit: Kate was pictured wearing the £570 Ralph Lauren blazer in March 2011 when she teamed it with brown boots and a matching handbag, right, but today went for a more summery look with wedges Marian Wyn-Jones, High Sheriff of Gwynedd, said: "We were talking about the joy she was having from George and how quick he was changing, she couldn't quite believe it. She's enjoying every minute of it. He's getting quite huge, she said. But it seems the Duchess has been finding time to re-start her fitness regime. Will Stewart, park warden at Holyhead Breakwater Country Park, where the gruelling three-day Ring O'Fire race started, said the Duchess told him she was "genuinely interested" in doing some more walking around the area, "especially after the baby." First official outing: Kate was described as looking 'absolutely gorgeous' by locals attending the event High Street choice: The Duchess recycled a top from Zara she last wore when she was five months pregnant He said: "She said she wants to get back into shape. Although aides have remained tight-lipped about her fitness regime, Kate is sporty and is known to have kept fit by walking her dog, Lupo, and taking part in ante-natal yoga classes, which are said to help women regain their figure by "training" muscles to snap back into shape. Sarah Barrett, managing editor of website BabyCentre UK, said: "Kate looks fantastic - and we wouldn't be surprised if a little yoga was part of her secret." 'Fourth' trimester style: Kate's outfit choices since becoming a mother As she left the hospital with newborn Prince George, Kate wore a bespoke Jenny Packham dress The following day as she drove to her parents' home, she wore a maternity dress by Seraphine Seraphine was again her shop of choice when she posed for the first official family portrait with Prince George Seraphine sales soar: The dresses have been in demand since they were seen on the Duchess. The floral print version is £50 and the pink £46