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The Duke of Cambridge , who served in the RAF as a pilot, climbed into the cockpit of a Typhoon jet as he visited one of the bases at the forefront of the UK's air defence. William spent ten minutes in the cockpit discussing the controls and the aircraft's capabilities with Wing Commander Andy Chisholm – a decade after he flew in the back seat of the fighter from the same station. The Lincolnshire base is one of two which provide 24 hour-a-day, seven days-a-week fighter cover to intercept threats ranging from Russian bombers to commercial airliners suspected to have been hijacked. The other is RAF Lossiemouth in Scotland.

As well as Coningsby's NATO Quick Reaction Alert (QRA) role, the base trains Typhoon pilots and William met with trainees as he visited 29 Squadron. The Duke, an Honorary Air Commandant at the base, also learned about how schoolchildren are getting involved with life at RAF Coningsby. Coningsby is home to a new engagement centre for the local community - the first of its kind at an RAF facility - including a classroom to teach science, technology, engineering and maths. The royal has made multiple visits to RAF Coningsby in recent years and spent a week based there in 2008 as he was given an introduction to the three branches of the armed forces.

GETTY Prince William visited the Royal Air Force (RAF) Base in Coningsby, in Lincolnshire

As William visited the RAF base his pregnant wife the Duchess of Cambridge attended a separate engagement in London where Kate officially opened the new headquarters of children's mental health charity Place2Be. The visit is expected to be one of the 36-year-old's last solo appearance before she takes some time out before welcoming baby number three in April. Kate looked glamorous in a recycled blue lace Seraphine cocktail maternity dress, which she wore just weeks ago during lunch with the Norwegian royals in Oslo. She teamed her outfit with black Stuart Weitzman heels and a small Mulberry clutch bag.

Duke & Duchess of Cambridge pictures Thu, April 26, 2018 Pictures of the Duke and Duchess of Cambridge's love story from the Royal wedding in 2011, to Prince George's first birthday in 2014. Play slideshow REUTERS 1 of 100 The Duke and Duchess of Cambridge and their newborn son outside the Lindo Wing, April 23, 2018

The pregnant duchess was in London to launch the charity's building, which will allow more counsellors, teachers and school leaders to be trained and provide a new home for the charity's research and evaluation teams. The mother-to-be showed no signs of slowing down as the visit marked her 40th public engagement this year, despite being weeks away from welcoming baby number three in April. Meanwhile Prince Harry is visiting the motor racing circuit of Silverstone in Northamptonshire. The ginger royal, who is Patron of the Silverstone Experience, will visit the site to officially mark the start of construction of the project.

GETTY Prince William has made multiple visits to Coningsby in recent years

GETTY William's wife Kate, the Duchess of Cambridge was in London to open a charity's new headquarters