The Nailers won away at both Stamford and Chasetown to secure the play-off title.
Black told The Derbyshire Times: “Everyone was a bit apprehensive at the start of the season after the two curtailed campaigns and nobody was really sure how things would pan out.
"But we were up there for most of the season alongside really strong sides like Ilkeston, Halesowen, Chasetown and Stamford and although we couldn’t maintain our challenge for the title, our next aim was the play-offs and we earned our place.
"We were underdogs for both play-off games which suited us in some ways but we also felt we could beat anyone in a one-off match and that the league positions didn’t matter at all.
"Stamford were adamant they’d push hardest to finish second as they wanted to play us. That galvanised our lads and no team talk was needed from me.
"We embraced that game and the Chasetown match, had no fear and handled it really well. I’ll never forget these last few weeks, it’s been unbelievable.”
Belper weren’t the only side that finished in fifth place to earn promotion.
Marine did the same, finishing fifth in the NPL West Division, and then beating Workington and Runcorn Linnets away to go up.
They join the respective champions of their divisions, Ilkeston Town and Warrington Rylands, in going up to step 3 - along with Liversedge and Marske United from the NPL East Division.
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