Gary Setchell’s men came back from being 3-1 down at half time, to level with 15 minutes to go and secured victory with two late goals.
"Terrible, awful, horrendous!” said the manager about their first half performance, in a club interview afterwards.
“They were told that at half time in no uncertain terms. Second half it was roles reversed and we were really good and scored four great goals. That typified the season really, that never say die attitude.
"We did everything we could and it’s nice to lift the trophy at the end of what’s been a memorable season.
"We dug in and showed why we are league champions and the best team in this league and I hope we have represented that well today.”
The Division One South champions took the lead after 20 minutes in Saturday’s match, watched by a disappointingly low crowd of 302 at the Eyrie.
Plymouth Parkway made it 2-0 inside half an hour before Dan Walker pulled one back for the Eagles for 2-1.
The visitors then restored their two-goal cushion just before half time.
It took until 20 minutes into the second half for Craig Mackail-Smith to give Bedford some hope at 2-3 and Hugh Alban-Jones equalised in the 75th minute setting up an exciting last quarter of an hour.
Just four minutes later Rory McAuley made it 4-3 to the hosts and Mackail-Smith made sure of the victory in 90th minute for a final score of 5-3 to the Southern League Division One Central champions.
Reflecting on a very successful season and move up to Step 3, Setchell said: “I’ll look back at this season as job done. I was asked to get us promoted within two years.
"We know we are going to lose games next year, we know it’s going to be competitive and every point we win is going to be hard-earned, but we are going to be capable of competing, I’m sure. Our first year at Step 3 will be very stressful, a big test of the players’ character – and mine.
"Then we have got to get ourselves into a position like we were this year at Step 4 – and who knows where we can be in two or three years.”