Bridgefield seemed to have the edge in the later stages as they went from 8-8 to 10-8, then 11-9. But this sparked an Ealing revival in the final quarter, goals by Rumen Kurtev, Sam Roberts and Sarpel Ustunel briefly earning an 12-11 advantage before the late Cadwallader strike.
Hamish Crichton was the star of Cambridge's 14-10 victory over Castleford, scoring seven times.
Three goals by Nigel Greenwood helped Birmingham wipe out a 6-4 half-time deficit against Worthing to clinch a 13-8 win. Southampton led Portobello 7-6 at one stage but the Scots dominated in the later stages to triumph 15-10. Luca Pollock scored three and there were two apiece for Hadrien Collineau, Neilson Rutherford, Ben Scott and Andrew Melville.