2 Grens and 1 sniper versus any combination of starting Brits units, who do you think is gonna win the engagement?
Replace Brits with any other faction and the other faction would lose just the same, werh sniper OP. That's all there is to it.
3 rifles with no upgrades < 2 grens + sniper
3 cons < 2 grens + sniper
It depends on skill of course as well, what position they are in, etc.