Speaking on Sunday with Laura Kuenssberg, the former Cabinet Secretary said leadership transitions are "enormously disruptive".
British Transport Police says the collision, which killed a train driver, is being investigated.
For the first time, the annual financial report for the royals will include how much tax is paid by the monarch.
After a slightly cooler Saturday, temperatures will rise again, possibly touching 36C by Tuesday with a Met Office amber extreme heat warning set to come into force.
Two people were injured close to a mosque and a man was later seen battering the door of a pizzeria as members of the public run away.