Farsley Celtic

Sinnott was not out of football for long, and moved into management with non-League Farsley Celtic in June 2003.^[5] His first success with the club was a third-place finish in the Northern Premier League First Division in 2003–04, which earned the club promotion to the Northern Premier League.

Sinnott would have achieved another promotion in his second season at Throstle Nest as Farsley topped the Northern Premier League at the end of the season. However, this was only on the FA's decision that Spennymoor United's records were expunged after they folded. The other clubs in the promotion mix appealed and the FA reversed their decision to expunge the results, leaving Farsley in third place and having to compete in the play-offs. Despite a 1–0 semi final win over Whitby Town, they lost in the final to Workington on penalties.

"I know the players aren't feeling that way at this moment in time – they are hurting – but they should be proud of themselves. Once the dust settles they can look back and realise they could have got promoted this season – twice. I couldn't have asked for any more from them. They have shown they have got what it takes to win this league and operate at a higher level. It's a long drive home but at least I can make it knowing we will move on from here without a shadow of a doubt."

— Sinnott remained full of positive energy despite the play-off defeat.^[6]

Another promotion was achieved in 2005–06, as Sinnott and Farsley bounced back from their play-off set-back. This time Farsley finished fourth in the regulation season before defeating Marine 1–0 and then North Ferriby United 2–1 in the final. Sinnott also added the West Riding County Cup to Farsley's trophy cabinet for the tenth time in the club's history, as they made it a double winning campaign in 2005–06.

The 2006–07 season saw Sinnott steer Farsley to a third promotion in four seasons. Despite finishing fifth in the Conference North, Lee lead the club to victory in the playoffs ensuring Farsley Celtic's first ever appearance in the top flight of Non-League. In the play off campaign, Farsley beat favourites Kettering Town in the semifinal, before going on to beat Hinckley United in the final played at Burton Albion's Pirelli Stadium. In the final Farsley Celtic had been 3–2 down with just over ten minutes remaining before two late goals saw a remarkable comeback and a 4–3 victory.

Farsley's three promotions under Sinnott and the declines of Bradford City and their local rivals Leeds United meant that just one and two divisions separated Farsley from its neighbours, when seven years ago six divisions separated them.

Port Vale

In October 2007, Sinnott was linked with the vacant job at League One team Port Vale, and on 1 November 2007 Farsley Celtic's chairman Andrew Firbank told fans that Sinnott would soon be leaving the club.^[7] However, hours later, confusion arose when Sinnott denied resigning.^[8] Five days later he was named the new Port Vale manager, ending the speculation about his future.^[9] Prominent backroom staff member Dean Glover had hoped to gain the management spot himself, and so pondered resigning from the club,^[10] but eventually chose to remain as Sinnott's assistant.^[11] The only significant staff member Sinnott was allowed to bring in was scout Steve Joesbury.^[12] In his first league game in charge Vale lost to local rivals Crewe Alexandra. Sinnott achieved his first win in charge of the club at Morecambe in the FA Cup First Round, with Port Vale winning 2–0. However, the Second Round held embarrassment for both Sinnott and the club, as Southern League side Chasetown (an eighth tier team 101 league places below the Vale)^[13] picked up a 1–1 draw at Vale Park,^[14] before making a giant-killing with a late goal on their home ground, after Luke Rodgers missed two penalties.^[15] Sinnott warned of big changes at the club.^[16] He signed Chasetown duo Chris Slater and Kyle Perry,^[17] and heavily exploited the loan market. He ultimately proved unable to save the club from relegation, and they were relegated on 12 April 2008. With only 38 points from 46 games, they finished ahead of bottom-placed Luton Town only thanks to a ten-point deduction inflicted upon Luton. In the summer ten players left or were offloaded by Sinnott, as he attempted to make room for new signings.

To make a success of the 2008–09 season, Sinnott brought in former Hereford United defender John McCombe,^[18] and former Middlesbrough midfielder Steve Thompson.^[19] Both players cited Sinnott as their reason for joining the club.^[20][21] He also added experienced defender Sam Stockley (Wycombe Wanderers);^[22] attacker Rob Taylor (Nuneaton Borough);^[23] midfielder Anthony Griffith (Doncaster Rovers);^[23] and attacking midfielder Louis Dodds (Leicester City) to the squad.^[24] Lee Collins also joined on an extended loan from Wolverhampton Wanderers,^[25] and would sign a permanent contract with the club in January.^[26] He appointed Stockley as his captain.^[27] The team continued to struggle, and on 18 September Sinnott admitted that "we are looking to improve, without a shadow of a doubt".^[28] However, a 4–1 home defeat to Macclesfield Town two days later would prove to be Sinnott's last game in charge. He was sacked two days later, with the "Valiants" lying in 16th place.^[29] Three months on from his sacking, the club were yet to reach a compensation settlement with Sinnott,^[30] before an agreement was reached in February 2009.^[31] The club went on to finish the season in 18th place under Dean Glover. Despite the poor results Vale picked up during his reign, many of Sinnott's signings would become key players for the club over the next few seasons.

Bradford Park Avenue

Sinnott was linked with a vacant position at newly promoted Northern Premier League side Bradford Park Avenue at the end of 2008. The club were unwilling to pursue the interest because of Sinnott's unresolved contract with Port Vale,^[32] and instead appointed his former Farsley assistant and successor John Deacey.^[33] However, despite Sinnott still taking legal action against Port Vale, Park Avenue appointed Sinnott as their new manager just one month later; Avenue were 11th in the Northern Premier League Premier Division at the time of his appointment,^[34] with Deacey standing aside to become Sinnott's assistant once again.^[35] Sinnott's first game ended in a 2–0 defeat to Eastwood Town.^[36] By the end of the season Avenue were in seventh place, two points and two places outside the play-off zone. He admitted that "the quality of the UniBond Premier is higher than I remember it to be three or four years ago. You don't get any freebies, without a shadow of a doubt."^[37]

He left by mutual consent in October 2009, after a summer spending spree failed to produce results on the pitch for the 2009–10 season.^[38] Avenue recovered to finish the season in second place under Deacey, though lost to Boston United in the play-off final.

Altrincham

In May 2011, Sinnott was announced as the new manager of Altrincham, a club that had just been relegated from the Conference National into the Conference North.^[39] The club finished eighth in the Conference North in 2011–12, before securing a play-off position with a fourth-place finish in 2012–13. They were beaten 4–2 by Brackley Town in the play-off semi-finals. The "Robins" again qualified for the play-offs in the 2013–14 campaign, and went on to secure promotion with a 2–1 extra time victory over Guiseley in the play-off final.^[40] Altrincham finished 17th in the 2014–15 season, comfortably away from the relegation zone.^[41] He left Altrincham on 9 March 2016, following a run of seven league games without a victory that left the club 21st in the table, one point adrift of safety.^[42] His assistant, Neil Tolson, was appointed as his successor but could not save the club from relegation.^[43]

Gainsborough Trinity

On 13 February 2018, Sinnott was appointed as manager of Gainsborough Trinity, who were then just inside the National League North relegation zone.^[44] The "Holy Blues" ended the 2017–18 season in 20th position and were relegated to the Northern Premier League Premier Division. He remained at The Northolme for the start of the 2018–19 campaign, but was sacked exactly one year into his appointment, following a 5–0 defeat by league leaders Farsley Celtic which left Trinity four points outside the play-offs.^[45]

Playing statistics

Source:^[49][50]

Managerial statistics

As of 13 February 2019^[51]

as a Player

Individual

• PFA Third Division Team of the Year: 1990–91

Huddersfield Town

• Football League Second Division play-offs: 1995

Watford

• FA Cup runner up: 1984

as a Manager

Farsley Celtic

• Northern Premier League First Division third-place promotion: 2003–04
• Northern Premier League play–offs: 2005–06
• West Riding County Cup: 2006
• Conference North play–offs: 2007

Altrincham

• Conference North play-offs: 2014^[40]