In London and South East England, where Tesco first began offering same-day deliveries back in 2014, they're available any day of the week. In other regions, though, where the option will be available by the end of August (at the latest), Sundays will be the delivery drivers' day of rest.
Like many retailers, Tesco is working towards making its deliveries more convenient and immediate. The supermarket launched one-hour deliveries for up to 20 items in London last month, drawing level with Amazon and Sainsbury's in the capital. Amazon's Prime Now service offers a large number of products, including groceries, for one-hour delivery in several major UK cities and their surrounding areas. This complements Amazon Fresh, a separate service for the same-day delivery of food and other essentials, but this isn't available nationwide either.
Tesco isn't the first competitor to beat Amazon to the punch, mind. In 2015, Argos achieved something of a first by offering UK-wide, same-day deliveries on tens of thousands of its products, showing that Amazon's dominance in online shopping doesn't mean it can't still learn a thing or two from high-street mainstays.