For example why project Ukraine is so important to the British Empire,]
The British Empire peaked in 1902 when it just about managed to win the Boer War. There after it lost power and influence even, as for a while, its nominal territory increased (post WW1 mandated territories) 20 years after the Boer war the metropolitan part of the empire got smaller when the UK withdrew from the greater part of Ireland. To a great extent and not always easily recognised the British empire conceded control to the USA during and ever since WW2