Can Britain still defend itself? It sounds like the sort of question once heard in gloomy pubs from men who owned atlases and distrusted decimalisation. Yet here we are, asking it seriously.

In this episode of Mark and Pete, we look at Britain’s armed forces, the shrinking Army, shortages of personnel, ageing equipment, thin ammunition stocks, delayed defence spending and the uncomfortable possibility that the United Kingdom has spent decades assuming somebody else would deal with the unpleasant bits.

Britain still has nuclear weapons, aircraft carriers, submarines, Typhoon jets, intelligence capabilities and capable servicemen and women. This is not a story about helplessness. It is, however, a story about whether a country can keep cutting, postponing and reorganising defence while still expecting the machinery to work when needed. Governments have become fond of strategic reviews. Soldiers, one suspects, would also quite like ammunition.

Pete and Mark discuss whether the British Army is now too small, whether the Royal Navy has enough ships, how drone warfare has changed the battlefield, and why conflict is no longer confined to tanks crossing borders. Cyberattacks, sabotage, undersea cables, satellites, energy infrastructure and misinformation all belong to the defence of the realm now. The castle walls have become invisible, which makes neglecting them wonderfully easy.

There is also the moral question. A nation cannot praise its armed forces on ceremonial occasions, send them into danger, and then house families badly, delay procurement and hope recruitment improves by magic.

The episode takes its theme from Psalm 127: “Except the LORD keep the city, the watchman waketh but in vain.” That verse does not excuse poor preparation. Quite the opposite. The watchman must still watch. The city must still be guarded. But national security cannot finally rest in weapons, budgets, speeches or polished men standing beside flags.

Can Britain still defend itself? Probably. But “probably” is not usually the word one wants printed across a defence policy.