pped ▁in ▁ 1 8 8 7 . ▁ ▁( c ) ▁ 7 ▁ft ▁ 6 in ▁driving ▁wheel , ▁H - class ▁Special ▁Blo om ers . ▁Three ▁examples ▁were ▁built ▁by ▁Wol ver ton ▁Works ▁in ▁ 1 8 6 1 ▁with ▁ ▁driving ▁whe els ▁together ▁with ▁Mc Con nell ’ s ▁pat ented ▁fire box , ▁which ▁were ▁intended ▁for ▁the ▁fast est ▁express es . ▁They ▁were ▁heav ier ▁than ▁had ▁been ▁planned , ▁so ▁a ▁further ▁two ▁engines , ▁ordered ▁and ▁under ▁construction , ▁were ▁cancel led ▁in ▁February ▁ 1 8 6 2 . ▁This ▁led ▁to ▁Mc Con nell ’ s ▁immediate ▁res ignation . ▁The ▁three ▁completed ▁engines ▁( N os . ▁ 3 7 2 / 3 / 5 ) ▁went ▁into ▁store , ▁so ▁hardly ▁ran ▁in ▁their ▁original ▁state . ▁One ▁of ▁them ▁( No . ▁ 3 7 3 ) ▁was ▁put ▁on ▁show ▁at ▁the ▁International ▁Ex hib ition ▁in ▁South ▁K ens ington ▁from ▁May ▁to ▁November ▁ 1 8 6 2 . ▁ ▁After ▁re building ▁with ▁normal ▁bo ilers ▁in ▁ 1 8 6 6 / 7 ▁they ▁worked ▁until ▁withdraw al ▁in ▁ 1 8 8 0 ▁and ▁ 1 8 8 2 . ▁Many ▁years ▁later ▁they ▁were ▁described ▁as ▁" Extra - large ▁Blo om ers ". ▁ ▁Rep lic as ▁ ▁An ▁accurate ▁full - size ▁non - working ▁rep lica ▁was ▁built , ▁by ▁app rent ices , ▁for ▁static