In an effort to improve the steaming capabilities of the class the Bristol Bath Road allocated 1009 , " County of Carmarthen " spent a period at Swindon Works from 1954 into 1955 where it was fitted with an experimental and temporary form of " stovepipe " chimney prior to it then receiving a more attractive design which, however , appeared rather flat in comparison with those on the " Kings ".
Whilst at Swindon 1009 underwent tests on the main line with the Great Western Dynamometer Car and the massive wooden shelter shown here was fitted to afford protection to the engineers riding inside who would be monitoring the various instruments which would have been fitted to the front of the smokebox