Exist where the supply infrastructure required makes it uneconomic to have several suppliers, for example gas supply, water supply, railways and landline telephones. To have competing gas mains running side by side to every house in Britain would be completely uneconomic. For this reason, many analysts believe that natural monopolies should be in the public sector, i.e. state-owned. When privatised, there is a severe risk that monopoly power will encourage the supplier to charge high prices for poor services (exactly as happens with many train-operating companies). Nevertheless, it is possible that the profit motive might prove such an incentive to increase efficiency that customers will still be served better than when a natural monopoly is left in the hands of the government.