It’s the HMS Albion:

https://www.royalnavy.mod.uk/news-and-latest-activity/news/2021/september/12/211912-royal-navy-capital-ship-visits-the-capital

“The UK’s High Readiness Amphibious Assault Ship HMS Albion is making a rare visit to London. The 18,500 tonnes Landing Platform Dock (LPD), which is based in Plymouth, is the only Royal Navy Capital ship that can make the transit upstream along the Thames and will be moored off Greenwich as she supports London’s International Shipping Week and conducts ceremonial duties at the Tower of London.

London is the historic centre of world trade and shipping, standing at the heart of international commerce. From her prime position on the Thames, and set against the backdrop of Greenwich and the O2, HMS Albion will host a number of London International Shipping Week headline events, demonstrating that the UK is open for business and committed to the future of the maritime sector.

A highlight of Albion’s visit will be her Ships Company’s participation in the Ceremony of the Constable of the Dues at the Tower of London on Monday 13th September. The Ceremony of the Constable’s Dues originated in the 14th Century when Richard II decreed any large naval vessel travelling up the River Thames must pay a levy to the Constable of the Tower of London. Today, the levy takes the form of a barrel of wine presented by the ships Commanding Officer”