It has historic roots which is why I assume it is there - monarchs would have all these oaths and allegiances read to them at Westminster Hall. It was mooted to be done in 1937 and 1953 as well. A lot of this is quite fascinating, you can read it in Roy Strong's Coronation, about the historic perspectives, where elements of the service and purpose of it comes from, including things like this. It was suggested by an MP I believe way back, but to bring it to Westminster Hall as a declaration of allegiance AND support by the people. Sort of like when you are at a wedding, and asked to support and uphold the couple.
Do it if you wish, don't if you don't. I am American so I won't
![Laugh :LOL: :LOL:](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
but I know my family in England will probably but they are very much monarchists. Sorry, I am a nerd who enjoys the history behind all of this - it is why it was my degree!