Rolling Stock of the GNR
During most of the Victorian period, carriages for long distance services were six wheelers, those for suburban stock had four wheels (and were very spartan). Bogie stock was introduced in the late Victorian period, much of it on six wheel bogies. The famous varnished teak finish was retained for the whole existence of the company. The real revolution in all kinds of carriage was due to the appointment of Nigel Gresley.
The following year he produced new carriages for the Manchester service with elliptical roofs and bow-ends. They were very well received; they did not only look attractive and were comfortable to ride in but they were considerably lighter than the 12-wheel clerestory stock of the previous design. This design was adopted by for the ECJS. He went on to rebuild two ECJS six-wheelers as an articulated twin with bogies at either end and a single central bogie. Again this was very well received. Next came suburban articulated twins and although these provided fairly basic levels of comfort, they were vastly superior to the old four wheel stock which they replaced.
On the freight side of the business, as mentioned elsewhere, vacuum fitted vans were produced to enable a speedy service. Bogie brick trucks were produced for the thriving brick manufacturers based near Peterborough.
Thank you to Richard Barron for the above information.