How iron entered British ship construction

Did early British iron shipbuilders use angle iron for framing?

Yes, among several experimental uses of iron, but the change from wooden construction was gradual and varied by builder.

British shipbuilders accumulated experience with iron by adding reinforcement to wooden ships. Curved wooden supports required timber that had grown into a suitable shape, which could be difficult to obtain. Iron could be formed into the required shape, encouraging its use for supports and other structural pieces. Experience with those applications suggested further uses, so the transition expanded gradually. Some builders used angle iron and others experimented with different forms, although no particular yard is identified. Britain's greater volume of construction is offered as an explanation for its longer period of experimentation compared with the faster American transition.