It's the morning of one of the biggest Tower events in years – the Constable's Dues. It's a 700 year old tradition, but this year the spectacle is bigger than ever, with over 80 coordinated Royal Marine commandos, high speed boats racing along the River Thames, a Royal Navy helicopter fly past, and a Royal Marine marching band.

But early morning rehearsals, led by Deputy Governor Debbie Whittingham and Chief Yeoman Warder Rob Fuller, are not going to plan. Tower Constable – and former Marine Officer – General Sir Gordon Messenger has invited some of the most senior members of the Armed Forces to watch the Dues take place – and the pressure couldn't be higher for everything to run like clockwork.

But it isn't just the Marines on show today. Yeoman Gaoler Clive Towell has a special role to perform – challenging the Marine commandos at the Tower gate, a traditional security protocol to decide who can enter the fortress, all while wielding his 500 year old Gaoler's axe. It's a tricky balancing act, but Chief Yeoman Warder Rob Fuller is on hand to show him the ropes, having spent three years mastering the art of ceremonial axe carrying when he was Gaoler.

With minutes to go, crowds and VIPs line the Tower wharf and the action-packed Constable's Dues kicks off. It's a spectacle rarely seen at the royal fortress, and a thrill for the day's visitors. To cap his first Constable's Dues in office, Constable Gordon Messenger cracks open his barrel of port to toast with his Tower and Royal Marine colleagues.

Over at the raven enclosure, brand new Ravenmaster Barney Chandler has his first big test as a team of vets from London Zoo arrive to check up on the health of the birds. After they suggest a little refresh to the raven cages, Barney has difficulty winning the stubborn ravens around to his changes…

Meanwhile, the nearly thousand year old fortress is proving it still has stories to tell, as a team of conservators investigate some mysterious carvings in a former prison cell. They employ cutting edge laser scanning techniques on the ancient graffiti to help decipher what it says – and end up revealing an incredibly rare first hand account from a prisoner who was locked up in Tudor times.

But that's not the only prisoner memento etched into the Tower walls, Historic Royal Palaces Chief Curator Tracy Borman hunts down a carving by another Tower prisoner who found himself embroiled in one of the most notorious plots in British history – the Gunpowder Plot. Tracy investigates how the Tower played a crucial role in bringing down the plotters, and how they met their gruesome ends.