Watford are preparing to face Premier League champions Manchester City at Wembley live on BT Sport on Saturday in what is only their second FA Cup final in the club’s 121-year history.
Barnes featured in the first, a 2-0 defeat by Everton in 1984, and believes it cannot be overstated how important an occasion it could be for fans of the Hertfordshire outfit.
“The FA Cup is so special,” Barnes, speaking on behalf of BT Sport, said ahead of the final. “In terms of a single day of football, it’s the most special in the calendar.
“When you win the Premier League it’s across a season. If you play in the Champions League final, often it’s abroad. But for the FA Cup the whole country is taken over by cup fever.”
Barnes concedes that the FA Cup doesn’t carry quite the same weight today as it did during his playing days, partly due to many of the modern players involved hailing from overseas.
But the former England international feels that for Hornets supporters, the cup resonates just as much as it did in 1984.
Asked about his experience of playing in the final 35 years ago, Barnes said: “For the Watford fans, who are based about half an hour from Wembley, it meant so much.
“Because I’ve been brought up in that tradition it meant more. It’s different in other countries because the domestic cups in Germany, France and the Netherlands are almost meaningless in comparison with the league.
“So it’s not the same for foreign players but for English players it still means so much. And for the fans it’s still so, so important.”
The financial rewards that come with staying in the Premier League for a prolonged period mean teams now tend to prioritise safety from relegation over FA Cup success.
Leicester City, for instance, rested their entire first-choice XI for a third-round trip to Newport County in January - and were subsequently dumped out by the League Two side.
Wigan and Portsmouth, meanwhile, have both won the FA Cup in the past 11 years but dropped to the third and fourth tiers respectively after lifting the trophy.
Barnes understands the approach as a former player but believes most fans would trade a few years of stability for an FA Cup win every time.
“You think about who’s won the FA Cup, you don’t think about what teams stay in the league for eight or nine years,” Barnes added.
“If you have a decision to play in the league as a player I would select that. But the feeling of lifting that trophy is euphoria. Winning the FA Cup is huge.
“Even if you go out of a league you always assume you will win promotion back to it. You never assume you have a chance to win the cup.”
As for Saturday’s match, Watford are 5/1 underdogs to win at Wembley and deny City an unprecedented domestic treble.
Barnes, who would go on to lift the cup twice with Liverpool, sees only one way Javi Gracia’s men can win the match against a City side packed with world-class players.
“Watford have to do what Leicester did [in the penultimate Premier League match of the season] even though they lost 1-0,” he said.
“They have to defend deep, defend in numbers and hit them on the counter.
“Gracia will set up with a 4-5-1 and use hard-working midfield players. Watford will hope to catch them on the counter and use set pieces to hurt City.”
One player who could hold the key for Watford is talismanic striker and skipper Troy Deeney.
The long-serving forward scored a crucial penalty in the stunning 3-2 semi-final comeback win over Wolves and for Barnes, is just as important as Sergio Aguero is for City.
“He’s the one constant for Watford,” said Barnes of Deeney, who has been at Watford since 2010. “He’s an inspirational character for them.
“Aguero is all about what he does on the pitch but Vincent Kompany is more of the leader. Deeney exemplifies what Watford are all about on and off the pitch.”
City have completely dominated Watford in recent meetings, winning the last ten games between the two sides – a sequence that includes 5-0 and 6-0 victories at Vicarage Road.
But Barnes is predicting a much closer encounter at Wembley, albeit one that City will edge.
“Watford have to play to their strengths,” he added.
“They won’t outplay City so they must use set-pieces and hit them on the counter-attack. But ultimately I think it will be 2-1 or 3-2 to City.”
Watch the Emirates FA Cup Final live on Saturday from 4pm on BT Sport 2. Watch live on TV and via the BT Sport App. For more info visit BTSport.com.