Thompson crossed the whitewash twice as England scored ten tries with Rochelle Clark also impressing for her country.
England Women Head Coach Simon Middleton said: “We have trained together for a long time and we are really comfortable about our combinations. We have played two games with a lot of ball in play and it’s how we want to play.
“I was really pleased with our defence. There was a lot of intensity about us today and we really focused hard, our attitude was outstanding.”
England face USA next in Pool B. The match is live on ITV4 on Thursday 17 August from 2pm.
Meanwhile Shona Powell-Hughes and Dyddgu Hywel both played for Wales as they lost 15-0 to Canada. They face Hong Kong next on Thursday.