Tesco follows Sainsbury's in launching a one-hour delivery service in London. The latter supermarket's offering is also only available in the capital via mobile app, and carries a £5 fee for up to 20 items. Both are trying to compete with Prime Now one-hour deliveries, which has enjoyed a relatively unchallenged head-start. Amazon covers many UK cities and towns, offers more than 20,000 products in some places, and charges £7 for a 60-minute guarantee or nothing if you can wait up to two hours (though the catch is you need a Prime subscription to start with).

Tesco is starting out small by comparison, with the service limited (for now) to these central London postcodes: E1, E2, EC1, EC2, EC3, N1, N16, NW1, NW10, NW3, NW5, NW6, NW8, SE1, SE11, SW10, SW11, SW12, SW13, SW14, SW15, SW1, SW3, SW4, SW5, SW6, SW7, SW8, W1, W10, W11, W12, W14, W2, W7, W8, W9, WC1, WC2.