I still think there is a massive proportion of the country that would be loyal to the monarch and to their fellow countrymen/women..I'd be more interested to see how many people would heed the call if conscription was brought back in. I suspect there would be a lot of teddies getting thrown out the pram.
Especially nowadays with 24/7 media and social media influence, you could set the narrative to sign those who are on the fence up.