Britain must see being ditched by Donald Trump for what it really is: a great opportunity | Clive Lewis

A line has been crossed. There is a bold, progressive way to think again about our defence and investment, social spending and foreign policy

• Clive Lewis is the Labour MP for Norwich South

Little more than a year ago, Keir Starmer could be described as what Napoleon called a lucky general". But now, six months after a landslide election victory, lucky" is an adjective unlikely to be found anywhere near a prime minister more usually described as having made missteps and unforced errors. And yet, perhaps, amid this tumult - a shifting geopolitical landscape, an authoritarian to the west of us conceding to the imperial ambitions of another to the east - Starmer's luck holds. For the situation offers him an unparalleled strategic opening through which my government can find and define its purpose.

The prime minister himself has called this a once-in-a-generation opportunity". The paradigm has shifted. It will not return to normal". Most significantly, the shibboleth of atlanticism - that unshakeable belief that the US-UK relationship is always right and always in our interest - has released its grip on our political imagination. We are free to define defence and security on our terms. And - as an increasingly anxious public pushes defence up the league table of concerns - we must do so.