"Massively proud, for me to be named captain of my country is something that hasn't sunk in yet to be honest and it was a massive honour.
"With players coming in, the squad does gel together really well as it's such a talented squad and the coaches are wanting us to play the right way."
Tuesday's semi-final 11-9 win over Wales saw the Gloucester Rugby Academy trio of Underhill, Joe Batley and Will Safe start in the English back row.
Having his home comforts and teammates around him is a great nod to the Gloucester Rugby Academy and those that have helped the young players reach the stage that they are at.
"To be on tour with my club mates, and to start the game on Tuesday in the back row with both Will and Joe was a great thing, and really enjoyable for all of us.
"The fact that Gloucester are well represented in this squad is great testament to the work that Peter Buxton and Simon Lane are doing with the Gloucester Academy and what a bright squad we have there.
"With Bucko being a back rower and someone I look up to. He's a club legend and I will be delighted to emulate his career in any way."
Underhill, along with Lloyd Evans are two young players that made their bow in the Gloucester Rugby first team this campaign, both starring in the LV= Cup against London Wasps, as well as the Gloucester United side in the A League, and it's been a memorable season for the back-rower.
"I'm really pleased with how that has gone and I am very thankful for the club for putting their faith in me and giving me the chance to play and impress."
England lifted the FIRA European Championship title last season and Underhill recognises the pressures that brings on the holders as they adapt to the game in Poland and a new environment.
"Obviously there's the expectation and pressure to retain the title but we're excited to play and we are a grounded squad that shows we are only as good as our last game.
"Poland is not typically renowned for its rugby, and it's a sport that's not as big as football etc. But as a country, Poland has been really welcoming and friendly.
"At both our games so far (v Portugal and Wales) there has been a great crowd that have given us a great amount of support and the hospitality has been great.
"We've got an afternoon off today so we're going to go and explore Poznan, so something different to what we're used to"
On Saturday, England meet their Irish counterparts in the final of the tournament and Underhill admits his team are fully focused on the job in hand to secure silverware after Tuesday's narrow 11-9 win over Wales in Pobiedziska.
"We've not met them before, but the French are staying in our hotel and Ireland beat them in the semi-final so they're telling us about their game.
"Obviously we have the benefit of analysis of videos and all of that however, it's essential we focus on our game."