The Bulldog-class steam vessels (SV2) later reclassed as First Class Sloops, were designed by Sir William Symonds, the Surveyor of the Navy.

Inflexible was the third vessel to carry this name since it was used for an 18-gun sloop, launched by St John's at Lake Champlain on 1 October 1776 and whose fate is unknown.

[2] Scourge was the sixth named vessel since it was used for a 14-gun brig-sloop, launched by Allin of Dover on 26 October 1779, purchased on the stocks and foundered off the Dutch coast on 7 November 1795.

[3] Bulldog was the third vessel so named since it was used for a 16-gun sloop, launched by Ladd of Dover on 10 November 1782, made a bomb in 1798, converted to a powder hulk 1801 Breaking completed at Portsmouth in December 1829.

[6] The ships were laid down as follows: Inflexible - January 1844 at Pembroke; Scourge February 1844 at Portsmouth; Bulldog July 1844 at Chatham; and Fury in June 1845 at Sheerness.