Waterloo is the busiest railway station in the UK, handling 41 million passengers in the year to March 2022. It is also the UK's largest station in terms of floor space and has the greatest number of platforms.

Identifying the "largest" junction in the UK depends on whether you measure by the number of platforms, the volume of trains, or physical acreage. London Waterloo is the largest railway station in the UK by platform count, featuring 24 platforms that handle over 70 million passengers annually. However, in terms of complex track intersections and "junction" activity, Clapham Junction in South London is arguably the most significant; it is famously the busiest station in Europe by the number of trains passing through it, with up to 180 trains per hour during peak times. If measuring by sheer physical footprint, Edinburgh Waverley is one of the largest, covering over 25 acres in the heart of the Scottish capital. Looking toward the future, the Old Oak Common station currently under construction in West London is set to become the largest newly built station in the UK, designed to act as a massive multi-modal "super-hub" connecting the new HS2 high-speed line with the Elizabeth Line and the Great Western Main Line, eventually handling 250,000 passengers daily.