Inside the Tower of London

Return of the documentary going behind the scenes at the castle. As autumn arrives, the royal bodyguard of Yeoman Warders come together to commemorate one of the saddest moments in the Tower's history, the passing of Queen Elizabeth II, before announcing the formal proclamation of King Charles III.

It's March 2022 and the Tower is continuing work on its most ambitious installation ever — the transformation of the moat into a huge floral display to celebrate the Queen's Platinum Jubilee. Known as Superbloom, the installation has been three years in the planning and is the most complex operation the Tower has ever undertaken. As the team digs down into the moat, there's a rare opportunity for archaeologists to search for ancient treasures that have been discarded in the moat decades and centuries ago. This isn't the first time there's been a search for buried treasure in the Tower — yeoman sergeant Clive Towell discovers how diarist Samuel Pepys went digging in the Tower's cellars after a corrupt constable of the Tower was rumoured to have hidden gold in the Tower's grounds in the 1650s. Yeoman warder Lawrence Watts gives new recruit Tam Reilly a tour of the Tower of the places the tourists rarely see, including Sir Thomas More's cell behind a hidden door in the Queen's House, and the toilet built for Adolf Hitler when it was thought he could be imprisoned at the Tower after WWII. Historic Royal Palaces chief curator Tracy Borman uncovers a Catholic plot to assassinate Queen Elizabeth I, masterminded by Italian banker Roberto Ridolfi with one of the stupidest noblemen in history, Thomas Howard, Duke of Norfolk. The queen had Norfolk arrested and he eventually met a grisly end as he was executed on Tower Hill. Horticultural expert Prof Nigel Dunnett has designed the planting scheme for Superbloom. He and his team have to scatter 20 million seeds across the moat's 14,000 square metres to grow and flower in time for the Platinum Jubilee weekend in June. As if that wasn't hard enough, there's a new challenge — discouraging the Tower's greedy pigeons, who see Nigel's seed-sowing efforts as a giant buffet.

It's April 2022 at the Tower, and there are just five weeks to go until Superbloom, the Tower's transformation of its historic moat into a vast floral installation to celebrate the Platinum Jubilee, is due to open to the public. But one of the UK's driest springs has wreaked havoc on the 20 million flower seeds sown in the moat for the display — the ones that have germinated are weeks behind and large areas are still completely bare. Prof Nigel Dunnet, the horticultural expert in charge of Superbloom's planting scheme, has been watering for weeks to try to avert disaster, but it's clear more drastic measures need to be taken. Historic Royal Palaces head of public engagement projects Rhiannon Goddard has no choice but to put down an expensive and high-maintenance option — special preseeded turf that already contains growing plants — to give Superbloom the best chance of flowering in time for the Jubilee. But despite everyone's best efforts, Superbloom isn't ready for its official opening. So chief yeoman warder Pete McGowran reassures the world's press that it'll be worth waiting for. Ravenmaster Chris Skaife is keeping a close eye on the Tower's ravens, who are taking advantage of their popularity to steal visitors' lunches. Yeoman warder AJ Clark walks her new dachshund puppy: he's named Reggie after Reggie Kray, an infamous East End gangster who spent time in the Tower. Chief yeoman warder Pete and the Tower's resident governor Brigadier Andrew Jackson award the Beefeaters a special medal in honour of the Platinum Jubilee at an exclusive ceremony on Tower Green. And Historic Royal Palaces chief curator Tracy Borman follows the tragic story of Lady Katherine Grey, sister of Lady Jane Grey, condemned to the Tower and a life of unhappiness by Elizabeth I. A couple of weeks after the official opening, Superbloom can finally be seen in its full glory. A breathtaking sea of millions of flowers transforms the Tower's historic moat to the delight of visitors and Beefeaters.

Deputy governor Debbie Whittingham and yeoman gaoler Rob Fuller have spotted an impressive visitor berthed across the river from the Tower - it's a Japanese warship, which is on a world tour and is stopping off in the capital. Meanwhile, Historic Royal Palaces chief curator Tracy Borman investigates the bridges that connect the Tower to the south side of the Thames, including London Bridge and Tower Bridge.

Cameras focus on the events of June 2022, the start of the Platinum Jubilee weekend and the celebration of Queen Elizabeth II's 70 years on the throne. In the Tower's gift shop, sales assistant and royal superfan Allen Jones has been doing a roaring trade in Jubilee memorabilia. Meanwhile, senior official General the Lord Nicholas Houghton is preparing to retire. He reflects on his time living in such an extraordinary building.

On Thursday 8 September, news arrives that would change the nation's history. The death of Her Majesty Queen Elizabeth II is announced after 70 years on the throne. It's a time of deep sadness for the Tower staff and for the yeoman warders, some of whom have met the Queen in their role as royal bodyguards. As a royal palace, with special links to the Royal Household, the Tower enters a two-week official period of mourning.

The Tower has recently mourned the passing of Her Majesty Queen Elizabeth II and proclaimed King Charles III. Having seen 42 monarchs come and go, the fortress needs to make some important changes to mark the new King's reign - the Yeoman Warder's uniforms need to be updated and the Queen's House, where the Constable lives, must now be changed to the King's house.