The lack of incoming transfer activity during the 1965 off-season served to highlight the view at Griffin Park that Brentford's squad was strong enough to secure promotion to the Second Division during the 1965–66 season. The campaign began with a rousing 6–1 victory over local rivalsQueens Park Rangers at Griffin Park, courtesy of goals from John Fielding, Joe Bonson, Ian Lawther and a Micky Blockhat-trick. The win gave way to three defeats and a draw in the following four matches, but consecutive victories over Shrewsbury Town and Swansea Town in mid-September proved to be a false drawn. Brentford would win just one more league match before the end of 1965 and the team's plight was worsened by the departures of influential attackers Jimmy Bloomfield, Mark Lazarus and John Fielding after disputes with manager Tommy Cavanagh. Outside forwardJohn Docherty was bought back from Sheffield United for his second spell at Griffin Park in December 1965, but Brentford began 1966 entrenched in the relegation places. Misfiring forward Joe Bonson was sold in January 1966 and though manager Cavanagh was provided with the funds to purchase replacement forwardsBrian Etheridge, John Regan and Bobby Ross, the new signings failed to help the team convert draws into all-important wins, with four matches being drawn in March. Three consecutive defeats in early April left the supporters clamouring for Cavanagh's head and despite a brief respite after a 2–0 victory over Brighton & Hove Albion, a 5–0 defeat away to Exeter City on 16 April led chairman Jack Dunnett to dispense with Cavanagh's services. Youth team manager Ian Black won, drew and lost each of the following three matches in a caretaker capacity, before Billy Gray was appointed as manager. Gray began his reign with Brentford in 23rd place and three points from safety with five matches remaining. A 3–0 home defeat to Mansfield Town in his first match in charge effectively ended all survival hopes after the gap to safety opened up to five points. A draw and a win versus Watford and Bournemouth & Boscombe Athletic respectively in the following two matches put the Bees back within two points of safety, but defeats in the final two matches of the season sealed the club's relegation to the Fourth Division. Three club records were set or equalled during the season:
