The London pub triumphed 5-3 on penalties after a 1-1 draw in normal time at former Premier League champions Leicester City’s King Power Stadium on Saturday 2 June.
The Gun, managed on the day by former Leicester and Wales midfielder Robbie Savage, won £5,000 worth of TV and entertainment equipment and a year-long BT Sport subscription as a result of their cup winning exploits.
JamieMcDonald, who scored the match-winning goal for the Liver Vaults in last year’s Pub Cup final, opened the scoring for the Merseyside team – giving them a slender half-time lead.
However, after the break, the Gun fired back, bagging an equaliser shortly after having a man sent off.
McDonald also saw red before the 90 minutes were up. With the contest sent to penalties, the Hackney pub's players held their nerve, scoring all five of their spot kicks, to claim the 2018 title.
BT Sport pundit and manager of the Gun, Savage, who saw the Gun as the underdogs going into the Pub Cup final against last year’s winners, said: “At half time, I told them to believe in themselves, that they were the better team in the first half, they just didn’t take their chances but we played the better football and were on top.
“Going down to 10 men, they showed immense character, heart, desire to get back in the game and then win it on penalties.
“They showed great guts to step up and take a penalty and, on the night, they deserved it.
“Next time I’m in London I’ll definitely be going to the Gun for a drink, the BT Sport Pub Cup winners!”
Speaking to The Morning Advertiser, Savage added: "I used to go and watch Sunday morning and pub football a lot when I was in Wrexham, some of the quality you get there is great.
“Watching these guys play and the way they're organised, there are some very good players.
“When you see the standard of pub players – I don't want to use that phrase because they're better than that – you realise how hard it is to be a professional footballer and make a living out of it. There are some exceptional players.”
Fellow BT Sport pundit and former Wales international John Hartson, who was managing the Liver Vaults, added: “Sometimes you can underestimate Sunday league, grassroots, pub football but there are some players that only narrowly missed out on the professional level and still love the game and they take pride in winning still and keep themselves very fit.
“It’s a great advert for all the pubs across the country and fair play to BT Sport Pub Cup for putting something like this on.”
Hartson added: "I've no doubt that if some of these players had pursued football, training and everything else, they could have made a career out of it.
"They're a great bunch of lads and they take the thought of winning £5,000 and a year's free subscription of BT Sport for their pub very seriously. They're very committed to doing that for their local."
This year’s BT Sport Pub Cup saw 64 teams take part in regional heats at seven football grounds across England and Scotland, including Goodison Park, Easter Road and Hillsborough.
The eight regional heat winners earned a place in the semi-finals at the National Football Centre at St George’s Park where they were split into north and south divisions, with the Liver Vaults and the Gun winning each respectively.
Savage added: "I was quite shocked by the standard, how good it was, how competitive it is and the willingness of every side to win and get to the final.
“I used to think about Sunday morning football, you see most of the guys hungover, some of the guys wouldn't turn up because they'd had a late night, but I've got to say this is completely different.
“It's been very professional, very organised and a fantastic initiative to give these guys the opportunities to play at some fantastic venues."