Willie McLean played for Airdrie, Sheffield Wednesday, Queen of the South, Clyde and Raith Rovers before managing Queen of the South, Motherwell and Raith Rovers whom he left to take charge at Ayr. He accepted the Ayr United vacancy in late January 1979.
There was a series of postponements due to the horrendous winter but managed a good 3-1 on his first match at Hamilton by 3-1 on 3rd February. Despite some good wins and finding themselves equal top of the league with Kilrmarnock they could not sustain it and finished eventually into a disappointing 4th place.
The following season there was still confidence that promotion would be attained, but with only 1 point after five games and being in bottom place caused massive dissent from the fans. Further defeats and losing some influential players left the club in dire straights and crowds plummeting. However some good buys such as Eric Morris and Derek Frye brought some hope. Both players began to score early and taking the club into a 16 match unbeaten run - just one short of the club record. With fourth place being occupied late on first place was out of site and second place a possibility with five matches to play. Sadly despite a good run, only 3rd place was achieved.
The following season (1980/81) began well with a 5-0 win over Motherwell. In the League Cup Morton, Queen of the South, Hearts and Hibs were beaten on the way to a semi-final place. Dundee was in the way but a 4-3 aggregate win for them denied Ayr a Cup final place. Ironically Dundee were beaten home and away in the league and eventually he had to settle for a 6th place. Early in 1981 Kilmarnock came to Ayr looking to appoint McLean but the manager rejected the move.
After a 1-0 defeat against Motherwell on 11th April McLean stated that finishing 5th or 6th in Division for a club like Ayr was a disgrace. 6th place was achieved finally. Nothing improved the following season with Ayr finishing in 6th place yet again. Season 1982/83 things began to get bleaker and when Ayr lost 1-0 to Dumbarton on 13th November the Honest Men were in last place. Fans were protesting and things became graver when Dunfermline beat Ayr in a four pointer on 9th April by 3-2 at Ayr. Barely 700 fans had turned up and it was clear that McLean was unable to get the club back to the Premier League and he resigned at a time when it was a struggle to even stay in the First Division.