The modern Carriage Shed in Glan y Mor Yard at Boston Lodge was a two-road shed built under the INCA Programme in 1990, adjacent to the Carriage Works and replacing the building which became the Loco Shed. It was extended to five roads in the period 2019-2021.
It was originally long enough for four carriages of the then-typical length (about 37ft) on each road. The landward road has the track embedded in a concrete floor but the seaward line is on steel supports above a lowered floor, for easy maintenance access to running gear and other underfloor equipment. In 2018-19 it was extended to accommodate five Superbarn-size carriages (about 43ft each) on each road. Due to the nature of the site it was necessary to build the extension on a curve. It has also had the roof raised to allow all Welsh Highland Railway stock to enter (including NGG16 locomotives).
Although new by FR standards this shed is already sometimes called the 'Old Carriage Shed' as a new three-road shed was built alongside in 2019, to accommodate ten carriages on each road. This is built on to the seaward side of the 1990 shed and extends to the new sea wall. It forms a perimeter to the site and provides a certain amount of shelter from wind and seaspray to Glan y mor and the Lower Yard. It is curved at both ends and will allow three full train rakes to be sheltered overnight without uncoupling. The pointwork for the new track fans at each end was installed in 2018-9 and to accommodate this the main line points for the entry to Boston Lodge have been moved further out along the Cob.
The structure was largely complete by October 2019. It is clad in unobtrusive green steel panels on the seaward side and the south end, but the west end and north side (Facing Boston Lodge) have ventilated wooden cladding.
The floor and tracks were not then completed, though a start had been made on one line before the Covid-19 shutdown in March 2020. The concrete beds for all three tracks were complete by August 2020. By November 2020 rails were laid on one road (22) which was declared available for carriage storage over the winter, and road 20 had also been railed in part. All three tracks were complete and the floor concreted to railhead level by the end of August 2021.