These were built in 1847 by Sharp Stewart for the Shrewsbury & Chester, and  came to the GWR in 1854 as part of the merger that formed the Northern Division and brought narrow gauge to the GWR. They were of a type known as Sharp singles that were delivered to a number of lines. One was converted to a tank engine, and a couple more had replacement cylinders but otherwise they were not greatly altered.  They were in service until the 1870s (1885 for the tank engine conversion). It's disappointing to note that no 14 was preserved at Wolverhampton until 1920 when it was finally broken up. A shame it didn't make it to 1928 and the York museum. One web page states that the GWR Directors didn't know it had been cut up and asked for it to be prepared for the 1925 Railway centenary at Darlington, but that might be just another rumour like the ones surrounding the loss of the Broad gauge locomotives some years earlier.

This sketch is more conjectural than I'm really comfortable with. I didn't find a drawing of one in as built condition, so I extrapolated from a drawing of the tank engine conversion and photographs of No 14 as preserved and significantly altered. I've found a suggestion that E L Ahrons had to do a fair amount of guess work in some of his series of drawings of early GWR engines in "The Locomotive" that are more familiar from the RCTS series (and which I am largely relying on for these very early types) so perhaps I am in good company.