Watford Shed was built in 1856 by the London & North Western Railway Company.

The original shed was a single track shed open at both ends and located at the north end of Watford Junction station
between the east side of the main line and the St. Albans branch line and there was a 42ft
Cowans Shildon turntable in the shed yard close to Watford No.3 Signal Box.

When the turntable was used to turn engines the overhang of engines fouled the track leading from Platform No.10 and the shed access, so the turntable could only be used when access to both was locked and a key had to be obtained from Watford No.3 Signal Box. (Picture in the 'Photograph' section)

The shed was extended in
1862 to a 2 track through shed and in 1872 the shed was demolished to make way for
enlargement of the station. A new brick built 3-track dead-ended shed with a slate roof was built and sited further north on the east side of the main lines.

The shed was enlarged in
1890 by the addition of another 3-track shed on the western wall of the first 3-track shed, making a total of 6 tracks. The facilities were upgraded with the addition of a coal stage and a 66,000 gallon water tank.

1937 the shed was re-roofed in a pitched style over each track with a single end gable.

The shed was closed
29 Mar 1965 and the footplate staff signing-on point was transferred to an office on platform 9.

1968 the shed was demolished and the site was used as a car park.