It is the business end of the season, and Essex are threatening to get busy. The next week or so holds out the promise of being a momentous one for the club. Modestly resourced but tightly run from their endearingly ramshackle Chelmsford HQ, the culmination of the summer brings opportunity on two fronts - a rare chance in the modern county game to enjoy simultaneous first-class and limited-overs success.

It is more than a decade since Sussex last managed to combine winning the Championship with taking home one-day silverware as well, beating Lancashire in the 2006 FP Trophy final. Currently top of Division One, Essex know they are in a scrap to hold off Somerset and claim a second title in three years; but before that denouement in Taunton, Vitality Blast Finals Day and the chance of a maiden T20 trophy.

Such an outcome looked more than a long shot back in August, when they had won just two of their first ten games. Essex were "dead and buried", says Ryan ten Doeschate, captain of the Championship side and a vastly experienced old lag in T20. Then came three wins and a tie from the last four and something in the universe aligned - not since the Blast had switched to a 14-game season, had a team sneaked through to Finals Day on such meagre rations.

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Success had not been signposted by Essex's recent T20 form, either. Last season brought just two victories and a seventh-place finish in the South Group, while the most recent of four previous Finals Day appearances came in 2013.

Ten Doeschate has been involved in them all, though none was particularly memorable from an Essex perspective. "Is it four?" he asks, furrowing his brow. On each occasion - against Leicestershire in 2006, Kent in 2008, Hampshire in 2010 and Northants six years ago - Essex were beaten in the first semi-final. The joke going around this time is that, with their game against Derbyshire scheduled for 2.30pm on Saturday, this is already the furthest they have been in the competition.

Ten Doeschate handed over the white-ball reins for this season to Simon Harmer, the former South Africa Test offspinner who has played such a vital role in Essex's Championship push. Harmer has overseen the return to Finals Day contention, with a largely similar squad to previous seasons - aggressive opener Cameron Delport the one significant addition.

It took a while to find the right balance for the team, with Varun Chopra eventually omitted and Tom Westley moving up to open alongside Delport. There have also been new roles for ten Doeschate and his old mucker, fellow Finals Day veteran Ravi Bopara, further down the order. But they seem to have found a formula at the right time.

"What's most exciting is we've turned things around with pretty much the same personnel," ten Doeschate tells ESPNcricinfo. "The last few years has been a bit of a struggle, Harmy coming in has shaken things up. The fact we haven't had two overseas for a lot of the games - the way the young guys have stepped into their roles.

"He's created a belief. He's gone with the approach, 'This is what we've got, we've got to make it work'. I think he's instilled a lot of confidence, particularly in the young guys. He wants the batters all to be positive, the change we've made a) in the batting order and b) personnel, I think that's made a big difference."

Essex will have to cope without their overseas players at Edgbaston on Saturday, with Adam Zampa and Mohammad Amir both unavailable (Amir missed almost half of the group stage with visa issues anyway). Netherlands seamer Shane Snater and young left-arm spinner Aron Nijjar have been added to the squad, and aside from ten Doeschate, Bopara and Adam Wheater, who went to Finals Day on more than one occasion with Hampshire, most of those on the bus up to Birmingham will be experiencing the occasion for the first time.

"The fact that most of the guys haven't been to it is probably a good thing, we'll go there tomorrow and it won't play on too many peoples' minds," ten Doeschate said. "The experience some of us do have, particularly myself and Rav, we've played a lot of games and hopefully we can spread that through the squad and prepare the guys for tomorrow. The fact it's been a season for turning things around, and we've done it against the odds. The position we were in with four games to go, we were dead and buried, virtually no way we could make it. That's a nice way to go into a final."

It was ten Doeschate and Bopara who were in the middle together as Essex sealed a quarter-final win over North Group winners Lancashire a fortnight ago. With 344 and 329 T20 appearances respectively, as well as experience in the IPL and beyond, they will hope to provide the big-match savvy as Essex seek that first semi-final success.

"There are very few games at Essex I've played without Ravi in the team. So it's always special to go out to bat with him. We are getting on, so we keep saying 'One more time, one more time'. But the form he's been in, and his approach to the game in the last six weeks - we don't like to single people out, but he's played a massive part in getting us to this stage of the competition."

As to whether Essex are overdue a limited-overs title, having last won the FP Trophy in 2008, ten Doeschate points out how difficult it is to combine success across the formats. Essex, of course, won the Championship in 2017, having been promoted the year before, and have set their store by red ball in recent years. Of the three other teams at Finals Day, Nottinghamshire have already been relegated in the Championship, while Worcestershire and Derbyshire are in the bottom four of the second tier.

"There's not many teams who do well in both formats," he said. "This year's a prime example. There's a lot of merit in saying it's hard to win both. But it's great that we have an opportunity to go there and win a cup that's long overdue."

With a rare double in prospect, can Essex be the exception that proves the rule? Ten Doeschate smiles and shakes his head. He will be 40 next year and hopes to still be playing for the club he joined in 2003 - whatever happens over the next week won't change his view.

"To dwell on results isn't healthy. I think the club can be immensely proud of what the team's done this year. The change in fortunes in white ball is something to be very proud of - and again the way we've competed in red ball. I'm not too focused on where we end up. It's five days - I'm not going to let five days define whether I think it's been a good season or not a good season. I think it's been a great season, and the chance to win two cups is fantastic. Of course we want to give it a crack."