Definition of "Sheffielder"

[…] and with the two promised Sheffielders, Driver Elliott and Fireman Lewis, we were soon on our way over the most unapproachably dreary region of the whole run, scarcely to be paralleled in the Black Country itself.

1949 March and April, F. G. Roe, “I Saw Three Englands–2”, in Railway Magazine, page 82