Brexit was fundamentally a battle of identity politics. On the one side, you had elderly grandmothers serving as volunteers at the local cathedral who regard British history and the imperial past with great fondness. On the other hand, you have a younger, more ethnically diverse population which views the British Empire with guilt and embarrassment and which valued its easy access to Europe.
Granny won. The irony is that Granny, in spite of her feelings about British imperial history, has no desire to engage with the rest of the world; she just wants to keep the foreigners out and the UK white. The empire that she values is a memory, not an ambition.