Starting from the outside of the front row, the Team BRM driver out-gunned Thomas Randle off the line and led until the chequered flag.
The pole-sitting Randle ultimately ran second for the duration of the 14-lap encounter, having been denied in his only serious attempt to take the lead on Lap 9.
Dream Motorsport's leading light tried a pass for the lead at the fast Turn 1 but was just held out by Lloyd.
Brown, who had been pressuring car #96 for some time, dived to the outside at Turn 2 and cut across the nose of Leeds, who half-spun and then straightened his rival.
The pair continued racing with positions unchanged before Leeds gifted third place with an error just a lap later.
Brown would return the favour with interest, spinning on Lap 10 and falling to eighth, where he remained for the balance of proceedings.
James Vernon finished fourth after starting ninth, with Nick Rowe completing the top five and Zane Goddard earning the P1 starting berth for tomorrow's top six reverse grid Race 2.