Sussex have secured their second Championship win of the season.

Olie Robinson returned his best figures of the season as they finally overcame dogged Middlesex resistance on the final day to triumph at Lord’s by an innings and 50 runs.

Robinson finished with 7-98 as the home side eventually succumbed after spirited knocks from James Harris and John Simpson had taken the match into a final hour.

Harris (80 from 211 balls) and Simpson (76 from 154) both registered their highest scores of the season, combining gritty defiance with some classy strokeplay as they put together a partnership of 103 for the sixth wicket.

But Sussex, having failed to complete victories on the final day of their previous two County Championship games, stuck at it and forced the win – although they were forced to call on the services of coach Jason Gillespie as substitute fielder during the closing stages.

With Phil Salt and Laurie Evans both off the field injured, the former Australia international – who retired in 2008 – donned his whites to take up a position inside the boundary rope and witness Sussex’s victory at close hand.

Resuming at 61-4 in the morning, Harris and Nick Gubbins helped to ensure that Middlesex would not be rolled over cheaply for a second time in the match as they compiled a stand of 58.

Gubbins (33) looked strong on the off side, forcing boundaries off Mir Hamza and David Wiese before the latter dismissed him with a questionable lbw decision, the ball appearing to be missing off stump.

Harris and Simpson saw Middlesex through to lunch, but the all-rounder had a fortunate escape in the first over after the interval, fending off a Robinson bouncer that rolled on to the stumps but left the bails in place.

He appeared to be unfazed, however, progressing to his third Championship half-century of the season with a sweet cover drive off Robinson soon after lunch and continuing to find gaps in the field as Middlesex kept the scoreboard moving.

With dark clouds overhead, Sussex finally utilised the spin of Will Beer for the first time in the match and he gave Harris another scare with an lbw shout that was turned down.

The partnership remained intact throughout the afternoon session, realising three figures when Hamza was recalled to take the new ball and saw it immediately dispatched to the boundary by Harris.

But the Pakistan seamer made the breakthrough with his first delivery after tea, finding the outside edge to end Harris’s stay of almost four and a half hours. Meanwhile, Simpson advanced to 50 before surviving a couple of close calls – an edge that Salt fumbled at second slip and then a leg before appeal by Wiese soon afterwards. Robinson, having taken the first four wickets of the innings, belatedly completed his five-for by castling Toby Roland-Jones for a breezy 17. Ollie Rayner (28 no) announced his arrival at the crease with a string of boundaries, but Robinson struck again when he persuaded Simpson to fish outside off stump, with Chris Jordan taking the catch. Ethan Bamber (4) soon followed and Hamza wrapped up proceedings by having last man Tim Murtagh (1) caught in the slips with 12.4 overs to spare.