 Indefatigable was the successor to the Invincible @-@ class battlecruisers . A number of options for large cruisers were considered for the 1906 Naval Programme , including the X4 design of 22 @,@ 500 long tons ( 22 @,@ 861 t ) with 11 @-@ inch ( 280 mm ) armour and 25 @-@ knot ( 46 km / h ; 29 mph ) speed , but in the end this programme consisted only of three ships of the Dreadnought type . A number of options were considered for the 1907 – 08 programme , ranging from 18 @,@ 100 long tons ( 18 @,@ 390 t ) to 21 @,@ 400 long tons ( 21 @,@ 743 t ) , but in the end battleships were again favoured and no battlecruisers were ordered until the subsequent programme year . 
