Lancashire 2 for 1 trail Leicestershire 155 (Gleeson 6-43) by 153 runs
Parkinson has been named in both the Test and T20 parties to travel to New Zealand ahead of the series this winter, and dismissed his twin for the first time in a first XI game to press home Lancashire's advantage.
Seamer Richard Gleeson, arguably one of Lancashire's unsung heroes this season, picked up first-class best figures of 6 for 43, which means Gleeson now has 44 Championship wickets in nine matches played, at an average of less than 22. Only Graham Onions, rested for this game, has more, with 45 in ten matches played.
Having exercised the away team's prerogative to bowl first, Lancashire's reward was almost immediate, as Foxes' captain Paul Horton, one of several former Lancashire players now with Leicestershire edged his first delivery from Gleeson straight to Keaton Jennings at first slip.
Fellow opener Hassan Azad had made nine, passing 1100 Championship runs for the season in the process, before he pushed a low catch back to bowler Gleeson, and the former Northants seamer struck for the third time when Colin Ackermann edged low to Liam Livingstone at second slip, reducing the Foxes to 16 for 3.
Gleeson should have had a fourth victim when George Rhodes, driving, edged to fourth slip before he had scored, but Rob Jones could not hold the head-high chance. Instead it was Tom Bailey, in the tenth over of an impressive opening spell, who picked up his first wicket when Mark Cosgrove tried to cut a wide but in-swinging delivery and succeeded only in edging the ball into his stumps.
Rhodes saw Leicestershire through to lunch without further loss, but was bowled through the gate by Gleeson in the first over after the interval. Harry Swindells also lost his off-stump to the same bowler soon afterwards, to reduce the Foxes to 82 for 6.
Harry Dearden and Callum Parkinson added 36 for the sixth wicket, but Dearden, on 30, also went bowled, driving outside a delivery from Matt Parkinson that spun back to hit the stumps, and shortly before tea Ben Mike was caught by Parkinson off the top edge at backward square off Livingstone.
Parkinson pinned his twin leg before shortly after tea before Gleeson bowled Dieter Klein to finish the innings.
Leicestershire did hit back. Chris Wright bowled Jennings with an inswinger that took the inside edge of the bat and hit leg stump - Jennings was also out first ball in the single innings he played against Leicestershire at Aigburth earlier in the season - but bad light and rain then saw play end with 24 overs remaining to be bowled.