Railway stations were the cathedrals of the 19th century, and Paddington holds a special place among them. It was one of the first to be built, completed in 1855.
What impresses now, next to its sheer scale, is that Paddington was a collaborative effort between engineer, architect and fabricator.
Brunel was unconstrained by track layout when planning Paddington and produced a stunning 31m central span flanked by two 20.7m side spans, reminiscent of a cathedral's nave and aisles.
Structurally, the iron and glass canopy could not be more simple and spare. Lateral stability was achieved by using the station's main masonry building on the south side, and propping through to the road embankment on the north side. Longitudinal stability was achieved by cross-bracing between the arches, as well as by very substantial and well-expressed wrought iron bracing between the column heads.
There are two 'floating' arches between each column. These are elegantly and efficiently supported by cross bracing - probably the most hard working elements in the structure. 'Bosses' under the ends of the floating arches are totally non-functional and mocked up out of timber, providing visual termination.
The arches are spaced at 3.05m centres, and it seems Brunel was drawing on his ship building experience.
He knew he could create light, broad spans using wrought iron ribs.
Brunel also dispensed with purlins, using corrugated iron as a structural spanning material.
Early drawings show a sparse station stripped of detail.
Decoration was added, but in nearly all cases it serves a dual role, stiffening or bracing structural elements at the same time as providing visual embellishment.