Oxford United are awaiting their first signing of the summer transfer window as their League One rivals begin to strengthen their squads. The U's are yet to make a move prior to the start of pre-season, with some of their rivals already getting business done early. Following their relegation from the Championship, Oxford United confirmed their retained list last month with 10 players departing and a further five returning to their respective parent clubs, including fan favourite Will Lankshear. Stockport County have been one of the busiest teams in the transfer market, securing the signing of Ryan Glover from League Two side Barnet on Monday. The addition came two days after the club appointed ex-Rochdale boss Jimmy McNulty as their new manager, taking over from Dave Challinor after their 4-1 play-off final defeat to Bolton Wanderers. Luton Town have also been swift in their dealings, apparently securing the addition of Bolton captain George Johnston on a free transfer. The Hatters apparently beat off competition from rivals Stockport, Sheffield Wednesday, and Bradford City for the 27-year-old defender. Reporter Pete O'Rourke states that Johnston is due for a medical in Bedfordshire. Plymouth Argyle have signed defender Alex Hartridge on a free transfer following the expiry of his contract at Burton Albion. It was reported earlier that the Pilgrims were interested in bringing back loan star Alex Mitchell from Charlton Athletic on a permanent deal, with Oxford United also apparently interested. Newly-promoted outfit MK Dons have also made strides in the market, signing defender Charlie Goode from last season's play-off semi-finalists Stevenage. Goode won promotion to the Premier League with Brentford in 2021. The 30-year-old joins on a free transfer having made 45 appearances for the Boro last term and will try and help Paul Warne's men make an instant impact on the third tier after finishing second in League Two last season. Oxford United's fans will be eager to see some new signings at the Kassam Stadium soon, as the club looks to bounce back from relegation and challenge for promotion back to the Championship.