The European Health Insurance Card (EHIC) formerly known as the E111, can be used to cover any necessary medical treatment due to either an accident or illness within the European Economic Area (EEA). The EHIC entitles the holder to state-provided medical treatment within the country they are visiting and the service provided will be the same as received by a person covered by the country’s ‘insured’ medical scheme.
All British citizens (it is only applicable to British citizens I believe, although I'm sure similar cards exists for other european citizens) are encouraged to carry the EHIC when travelling in the EEA, in additional to travel insurance. (It usually has to be renewed every few years).
In addition whilst it is not compulsory to have, I have heard many stories of Brits travelling to places like Spain on holiday, even though they had travel insurance, because they weren't carrying EHIC they encountered many problems with medical assistance/hospitalization etc.
For British citizens travelling within the EU, the only EU country where you do not need an EHIC card on you at the time of medical assistance and/or hospitalisation is when travelling to Malta. This is because a reciprocal agreement exists between the two countries for the medical treatment of it citizens.
For all other EU countries including Norway, Switzerland and Liechtenstein (if you are British at least) not having a valid EHIC card (even if you have travel insurance) on you at the time of such medical assistance could lead to very BIG problems.
It is also VERY important to note: You certainly CANNOT apply for a EHIC card (wrt being British) and expect to use it after a medical event has occurred in EU countries including Norway, Switzerland and Liechtenstein.
More info about EHIC can be found here: