Jon Macken named an unchanged team to the side that beat Ramsbottom United mid-week to seal their place in the final, and the theory of 'why change something that isn't broken' was definitely in the thoughts of the gaffer.
Boro did try to make openings in the first seven minutes. Scott Metcalfe's trademark advance down the left, ended in a whip across goal but to no avail.
The best attack of the first 15 minutes was when Tunde Owolabi won the ball from left-back Scott Lycett and drove inside from a tight angle, setting up his strike-partner Ben Wharton for a tap-in, but somehow the goalkeeper saved from point-blanc range.
But it was the visiting side who broke the deadlock in the 33rd minute. A deliciously floated cross from Dan Trickett-Smith went past the heads of the Boro back-four and Robert Stevenson was there to tap home.
It was a solid display at the back for the Blues, but their barricade nearly cracked at the end of the first-half when Owolabi played a teasing cross from Metcalfe and similar to Wharton, he wondered how he didn't convert what seemed to be a tap-in.
Macken must have given his players an inspiring team talk at half-time as Boro came straight out of the blocks with an equaliser. Substitute Matty Crothers was played in down the right by Kyle Harrison and his first-time cross across goal gave Owolabi an easy tap-in.
After pinball in the Leek Town area, Boro were left scratching their heads as to how they didn't take the lead three minutes later. Callum Grogan's flick towards goal looked in, but it was cleared by Jack Sanders.
57th minute and Leek almost found themselves back in-front. A wayward cross from Stevenson found it's way onto the cross bar and over. Ollie Martin would have had his heart in the mouth.
Then, the referee pointed to the spot for the home side, 63 minutes in, as Kyle Harrison was fouled by Lewis Short, and up stepped Ben Wharton to fire home the penalty to commence scenes amongst the Boro fans.
Sudden appeals for a penalty in the 77th minute as Stevenson went down inside the area as he looked to have been clipped by Harrison, but the referee Ben Atkinson did not give a second spot-kick of the day.
Nerves were set. Some fans were already chanting the sounds of 'we're going up', as others watched the nail-biting and tense last 10 minutes.
The away side's substitute Tim Grice tried a shot from 25-yards out in the dying embers of the game, and it looked to be going in. Martin, however, produced possibly his finest save all season onto the post and out.
95 minutes on the clock, and Leek found themselves through with Tricket-Smith as he only had the Boro number one to beat, but from out of nowhere, when all seemed to be lost - that man Metcalfe gave his last ounce of energy to force the ball clear. It was either a last-man sending off, or the most important tackle he would ever make - and it was the latter.
The reliance on a result from Brighouse Town FC, a long with the final whistle being blown at the Neuven Stadium confirmed Boro's promotion to the Evo-Stik Northern Premier League for the first time in 16 years. This was arguably the biggest day in the club's recent history.
16 years of hurt, gone
The 2002/03 season was the last time Boro were promoted to the seventh tier of English football, after finishing first in the old Evo-Stik North Division One(NPLD1))
Since that achievement, Boro were relegated in 2008, and have since finished no higher than 10th position for the past 12 seasons.
The runners-up finish for the Neuven-outfit was their highest standing for 22 years, when Boro were Champions of the NPLD1 in 1997.
Goals won it, but THAT challenge more so
The defining moment for Radcliffe has to be with seconds on the clock, when Scott Metcalfe was on the stretch and sent the ball out of the path of the last Leek attacker, who looked certain to finish a one-on-one.
It was defining, because last legs were seen, but it didn't matter. Metcalfe found the guts. The desire. The spirit. Everything the season was built on was in that challenge from Metcalfe. Tunde Owolabi and Ben Wharton were the match-winners in terms of the score-line, but alongside the back-four and goalkeeper Ollie Martin - Scott was the true saviour.
51 is the magic number
Owolabi and Wharton have been the prime firearms for Macken's side this campaign. The classic 'big man little man' partnership that we've seen in the 20th century has been at the forefront of the attack. It's been a throwback.
They've recorded a combined 51 goals this season. The same amount that the Boro scored in the entirety of the 2017/18 season.
It's been the perfect mix. Wharton's strength, potent finishing and positional smarts and Owolabi's speed, trickery and delicate finishing.
Ollie Martin, Matty Williams, Callum Grogan, Lewis Lacey, Matty Carr, Kyle Harrison, Lee Nevilleand Mason Fallon have all played a vital part in the Boro's base of the side. A solid defence with boasts only 34 goals conceded in all competitions this season.
Boro have had the goals to win them games, but this is a case of the defence being able to win you titles, promotions and having successful seasons.
The run-in showed why Boro deserved to achieve promotion, with just five goals conceded in the last 11 games.
Man of the Match - Lewis Lacy
Lacey was calm, composed, and remained solid when the going got tough for Boro. Deflating the counter-attack on countless attempts from Leek and was colossal in the air.
He, alongside Grogan and goalkeeper Martin have formed a formidable spine this campaign.