Yep, same can be said of manufacturing capability in general. If you don't have a manufacturing base then inevitably when there's a war you may find yourself unable to build defense components.

Supply chains are so diversified that self sufficiency is only feasible for countries the size of US and China.

Russia has been forced to cannibalize jet planes because sanctions have starved it of spare parts.

Even the US Navy gets its ships built in South Korea now.

Britain's remaining industries are very niche. With a small domestic market, you can't get economies of scale. You have to specialize.