£15 to climb the Big Ben this summer

[TomaTito]

You will need three of these to visit it

The guided tour to the Big Ben has always been free, but that is due to change this July, were visitors will have to pay £15 to climb the 334 spiral steps of the clock tower.

I wonder why they are changing this after 150 years of not charging any one. Is there any special event going on this summer over there?