I visited the Tower Hill Memorial for some photographs to update my Merchant Navy article: https://www.stephen-stratford.com/merchant_navy.htm
Some people fail to understand how you behave and treat a war memorial!
There is a notice by the memorial asking people to respect the memorial and keep it ship-shape and tidy, out of respect for the thousands commemorated.
There were crosses and poppies stuck to various points on the name panels. If you are commemorating a person listed on the memorial, you place your cross or poppy at the base of the appropriate panel. You do not stick the item to the panel!