Robinson's missed penalty persuaded Gloucester to opt for the catch-and-drive from line-outs close in but twice Gloucester failed to find a way through the Londoners' defence.
The early Pacific Andes business model--in which it supplied capital to boat owners in return for some of their catch--left it too close to fishermen who crossed the line.
Wales hit back after half-time as a fine pass back inside from Jonathan Davies allowed Halfpenny to break through, then a line-out catch and drive shoved Hobbs over.
But Anderson soon trapped Davies playing across the line, and Park nicked behind to give wicket-keeper Luke Sutton his fourth catch of five in the innings.
"When pros aren't putting well they're trying to force the ball into the hole instead of rolling the ball down their line and letting the hole catch it, " said Kevin Weeks, another notable short-game guru.