Would Britain accelerate Vanguard and the Lion class?

Would a Japanese defeat of the American battle fleet cause Britain to accelerate Vanguard and the Lion class?

Probably; Vanguard and the Lion-class projects would gain urgency once a modern capital-ship threat made their strategic value immediate.

The viewer asks whether Britain would respond to the loss of American standard battleships by rushing its own modern capital ships. Both Vanguard and the Lion class would probably receive greater urgency. The repeated delays to Lion kept the design available while Britain waited for technology and strategic need to become clearer. A Japanese demonstration against the American battle line would supply that need and make continued delay much harder to defend.