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The eponymous Weald Stone is a sarsen stone, formerly marking the boundary between the parishes of Harrow and Harrow Weald. It is located outside the Bombay Central restaurant, which was a former public house (previously known as the Weald Stone Inn and prior to that, the Red Lion), outside 328 High Road, Harrow Weald.

The Harrow and Wealdstone rail crash was a three-train collision at Harrow and Wealdstone station in London during the morning rush hour of 8 October 1952. 112 people were killed and 340 injured (88 of these being detained in hospital); it remains the worst peacetime rail crash in the United Kingdom.

An overnight express train from Perth crashed at speed into the rear of a local passenger train standing at a platform at the station. The wreckage blocked adjacent lines and was struck within seconds by a "double-headed" express train travelling north at 60 mph (97 km/h). A subsequent Ministry of Transport report on the crash found that the driver of the Perth train had passed a caution signal and two danger signals before colliding with the local train. The reason for this was never established, as both the driver and the fireman of the Perth train were killed in the accident.

The accident accelerated the introduction of Automatic Warning System - by the time the report had been published British Railways had agreed to a five-year plan to install the system that warned drivers that they had passed an adverse signal.

There are three pairs of running lines through Harrow and Wealdstone station, from east to west these are the slow lines, the fast lines of the West Coast Main Line, and the DC electric lines. In each case the "up" line is southbound towards London Euston, the "down" is northbound towards Watford and Birmingham.

The collisions involved three trains:

• The 7:31 am Tring to Euston local passenger train—9 carriages hauled by a steam locomotive-on the up fast line.
• The 8:15 pm Perth to Euston night express-11 carriages carrying approximately 85 passengers hauled by a single steam locomotive-on the up fast line-this train was running about 80 minutes late because of fog.
• The 8:00 am express from Euston to Liverpool and Manchester-15 carriages carrying approximately 200 passengers, double headed by two steam locomotives-on the down fast line.

On 8 October 1952, at around 8:17 am, the local train stopped at platform 4 at Harrow and Wealdstone station, approximately seven minutes late because of fog. Carrying about 800 passengers, it was busier than usual because the next Tring-Euston service had been cancelled. As scheduled, it had traveled from Tring on the slow line, and then for some utterly bizarre reason, had been switched onto the up fast line just before Harrow and Wealdstone - right into the path of the approaching night express from Perth.

At 8:19 am, just as the guard was walking back to his brake van after checking doors on the last two carriages, the Perth express crashed into the rear of the local at a speed of 50-60 miles per hour (80-100 km/h). Due to thick fog, it had passed a colour light signal at caution and two semaphore signals at danger, and had burst through the trailing points of the crossover from the slow lines, which were still set for the local train.

The collision completely destroyed the three wooden bodied coaches at the rear of the local train (where most of the casualties occurred), telescoping them into the length of one coach, and drove the entire train forward 20 yards (18 m). The leading two vans and three coaches of the Perth train piled up behind and above the locomotive.

The wreckage from the first collision was spread across the adjacent down fast line. A few seconds after the first collision, the northbound express to Liverpool Lime Street passed through the station on this line in the opposite direction at approximately 60 miles per hour (100 km/h). The leading locomotive of this train struck the derailed locomotive of the Perth train and derailed itself. The two locomotives from the Liverpool train were diverted left, mounting the platform, which they ploughed across diagonally before landing on their side on the adjacent DC electric line, one line of which was short circuited by the wreckage; the other line had its electric current quickly switched off by the signalman, thus preventing any further collisions. The leading seven coaches, plus a kitchen car from the Liverpool train, were carried forward by momentum, overriding the existing wreckage and piling up above and around it. Several of these coaches struck the underside of the station footbridge, tearing away a steel girder.

Sixteen vehicles, including thirteen coaches, two bogie vans and a kitchen car were destroyed or severely damaged in the collisions. Thirteen of these were compressed into a compact heap of wreckage 45 yards (41 m) long, 18 yards (16 m) wide and 18 feet (5.5 m) high. The Perth locomotive was completely buried under the pile of wreckage.

There were 112 fatalities, including the driver and fireman of the Perth express and the driver of the lead engine of the Liverpool express. 102 passengers and staff died at the scene, with a further 10 dying later in hospital from their injuries. Of the 108 passenger fatalities, at least 64 occurred in the local train, 23 in the Perth train, and 7 in the Liverpool train. The remaining 14 were unclear, but some of the fatalities may have been standing on the platform and hit by the derailed locomotives of the Liverpool train. A total of 340 people reported injury: 183 people were given treatment for shock and minor injury at the station and 157 were taken to hospital, of whom 88 were detained.

After the accident there was criticism that the layout of the track at Harrow and Wealdstone was arranged with the junction between slow and fast lines to the north of the station so that the Tring train had had to wait on the fast line instead of at the usual slow platform. The junction was subsequently changed.