The 40ft-long Excalibur crew-less vessel launched a US warhead in secret trials, copying the capability of more expensive and much larger manned submarines. The UK government says the launch of a heavyweight torpedo, jointly developed by the US and Australia, "marks a major advance in the future of submarine technology". Key points and original sources are listed below.

• The 40ft-long Excalibur crew-less vessel launched a US warhead in secret trials, copying the capability of more expensive and much larger manned submarines.S1

• The UK government says the launch of a heavyweight torpedo, jointly developed by the US and Australia, "marks a major advance in the future of submarine technology".S2