White text by front wheel is the name/address of the owner/operator of the bus.
Identity of company is a requirement for use for public carriage it is almost certainly the registered address/phone # of routemasterhire.com.
Quite likely the ripple is as a result of damage from hitting a tree branch.
It would also explain slight variation with the window.
This happens quite frequently with double-deck busses.
RM busses were designed so that as much as possible is either flat sheets or has a single curve rather that complex compound curves.
They are constructed of thin alloy sheets attached to a lightweight frame in a near identical fashion to aircraft construction.
This can make them susceptible to rippling or distortion of panels.
Mechanics might've decided that the ripples were not bad enough to fix or cause issues with safety or operation.