London has worse 4G availability than 15 other major cities in the UK, and has been beaten by the likes of Sheffield, Sunderland and Leicester in a report on mobile internet connection.
The findings from Which? and OpenSignal show that smaller urban hubs have better 4G coverage than the UK's largest cities.
London came 16th in the rankings, and Manchester came 12th. Meanwhile, Middlesbrough topped the list, followed in second place by Sheffield.
The data was collected from over 30,000 users of 4G, and the researchers took readings every minute a user spent walking around where they live. Smartphone users in Middlesbrough could connect to 4G 83 per cent of the time. Londoners, however, could only connect 73 per cent of the time.
Alex Neill, managing director of home products at Which?, said: "These latest findings underline the need for Ofcom to keep the pressure on mobile operators so that every part of the country gets a decent service on their mobile phone. Our mobile phone is central to how we live our lives and that is why it is so frustrating when we can't access emails or browse the internet on the go."
Last month, the City of London Corporation said it had found a solution to the problem of 4G blackspots in the Square Mile, with a new free, public wifi network.