Danaher has played for Irish for the past 10 years
London Irish flanker Declan Danaher believes the Premiership final is the biggest game in the Exiles' history.
Irish face Leicester Tigers at Twickenham on Saturday with the winner being crowned English champions.
Danaher told BBC Berkshire: "Without a doubt this is the biggest day in the club's history - bigger than winning the Powergen Cup seven years ago.
"It's a momentous day - a massive step which we've been threatening to take for a couple of years now."
Danaher, who has been at the club since 1999, said it was important to remember things had not always been as good at the club.
"We had a great year when we won the cup, but then we fell away and we were fighting relegation for a few seasons.
"It wasn't until Brian Smith came in that we finally found the belief that we could do something. I have dreamed about this, but for it actually to be happening is pretty cool.
"When things aren't going well or you're not playing, you doubt yourself. But you have to look back and remember days like the Powergen Cup final and believe that they can come again."
Danaher acknowledged Irish would start as underdogs but said the belief was there to win.
"Leicester are a great team. We're going to have to play out of our skins to get close to them," he added.
"We've always been close in games, so we've never had to change everything. We've stuck to our values and stuck to the way we've played and believed in what Toby Booth's wanted us to do. It's got us this far so we just have to believe a bit more."
Danaher will be the only London Irish player to have appeared in two finals at Twickenham and he said the supporters will play their part again.
"The support at the Stoop (in the semi-final against Harlequins) was unbelievable. It reminded me of the Powergen Cup final when it felt like there were 80,000 Irish fans there," he said.
"It felt like there were more Irish fans there than Quins and it drove us through the 80 minutes."
London Irish versus Leicester Tigers kicks off at 1730 BST on Saturday, 16 May and is live on BBC Berkshire.
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