The visitors threatened to upset the Police applecart when Dan Thompson gave them a second-minute lead.
But Charlie Collins responded in the ninth minute and went on to give the Met the lead on the houir.
Back came Bognor with a goal from Terry Dodd in the 70th minute, only for Knight to grab the winner four minutes later, lifting the Police from seventh to fifth in the table.
Lewis Francis scored after 19 minutes to give Romford a 1-0 home victory over Needham Market in Ryman North. They climbed two places to ninth.
Matt Poxon had hit the bar for Needham after only two minutes and the woodwork again foiled them late in the game when Ryan Charles hit a post as he tried to punish a defensive mix-up.
But Boro were generally on top and deserved to capture all three points.
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