The acting was amateurish, the dialogue was dire.
It was interesting to see that No. 3 Slip in Chatham Dockyard stood in for Harwich.
The worst aspect of the plot was the whole jet engine/supersonic flight thing, which was laughable. British jet engines were the best in the world at the time. The British supersonic project was the Miles M.52, for which work started in 1942. There was certainly no need for a German engineer. The test site in the tunnel was ludicrous. As for the "rivalry" with the Americans, they had been provided with Britain's research data, but eventually gave nothing back in return. Their first supersonic flight was with the Bell X-1, which was not an 800 mph jet but a rocket-powered aircraft that first exceeded Mach 1 at 700 mph. The M.52 was cancelled long before that.
All in all, a waste of my viewing time.