Saska is absolutely correct. I am surprised at the comments from some people here. The fact that the aircraft were insured is irrelevant Flaps One. You must carry proof of this on board the aircraft to show to authorities at other airports. Indeed that is how the CAA can prevent carriers flying in to the UK if there is no evidence of insurance cover.
The first thing I have to check when I get on board an aircraft is the documents in the envelope on the cockpit door. Unfortunately the fast turnrounds at easyjet often lead to pilots skimping on this check.