Britain would be 'comprehensively outgunned and outranged' in war with Russia, report says

The problem across NATO militaries is that each does not maintain a fully functional military, as they did when Europe was fighting each other. Rather they depend on their allies - chiefly the United States - for key aspects such as mobility, reconnaissance, and fires. This allows countries like the UK to either subcontract arms purchases or skip them all together. It is expensive to modernize and build new weapons systems, and many NATO countries divested from this after the demise of the Soviet Union.
On the bright side, so did the Russians. They've been making a lot of sound and fury about all of these whiz-bang weapons they've developed, but the truth is very few of them have been fielded and the cool-guy ammunition is too expensive for Russia to stockpile. So they chiefly go to war with Soviet-era stuff, which they possess copious amounts of.
That is why Ukraine was able to fight them to a stalemate. The Russians threw the house at them early and hurt Ukraine badly, but then had to halt to await resupply.

More than likely.

As WWII progressed it became evident that leadership, alliances, doctrine, combined arms, logistics, and air assets played a major role in the outcome of the war.