Gloucester number eight Zach Mercer says he is "done" with England for now after missing out on selection for the forthcoming Six Nations Championship.

He was also overlooked for a place in the World Cup squad last autumn.

The 26-year-old said he does not feel head coach Steve Borthwick "values what he can offer" as a player.

"I'm older, more mature, I put the international selection aside now, I'm done for the time being with that and I'm just going to focus on Gloucester," Mercer told BBC Sport.

Mercer played twice for England under Borthwick's predecessor Eddie Jones and was on the periphery of the Australian's squad before transferring to Montpellier in the French Top 14 in 2020, in a move that made him ineligible for selection.

He thrived in France and won the league title during his first year, and was named Top 14 Player of the Year in 2022.

After signing for Gloucester last summer, he was included in Borthwick's training squad prior to the World Cup in France but was dropped when the final squad was named.

He took part in another England training session earlier this month, having recovered from an ankle injury, and hoped to have done enough to have made the Six Nations cut.

"To come back and get given three weeks in a training camp and that was it, I was really disappointed with that," Mercer said.

"I've been open with Steve, I've told him my opinions on it. I thought I haven't really been given a crack which is what I feel like, to not even be given a game to try and prove myself is tough.

"I just don't feel like he values what I can offer as a player and that's me being honest, I don't think he values what I can bring.

"Obviously I don't fit into the system that he wants to run and, whether I agree with that or not, it is what it is.

"My focus now is on Gloucester and England can take a step aside for the moment."

Mercer said Borthwick called him on Tuesday to tell him he did not fit into his plans for the team.

"I said 'if you give me an opportunity you won't be able to drop me', I want this so badly that I know when I play he won't be able to take me out of the team," Mercer said.

"Like I said, he doesn't want to pick me right now, whatever reason that's for."

Mercer 'had enough of waiting' for England chance

Mercer spent five years with Bath before making the move across the Channel.

Few English players move abroad early in their career, so as not to harm their chances of playing internationally. For Mercer, he moved to France specifically to get away from it.

"I was so close but I never made it. I was always getting cut at the last minute," he said.

"I decided 'I've had enough of this' I wanted to go and do something different, I'm not sitting and waiting for an international call.

"Rugby is a short career, I wanted to go and do that, I wanted to do something that would put me out of my comfort zone."

With the pressure of England selection off the table, Mercer said he began enjoying rugby again and started to excel on the field.

"I remember my first meeting with [Mohed] Altrad [Montpellier owner], in front of the group he was just like 'you should be playing for England but you're not and you're here, just do what you do' - straight away the barriers were down," he said.

"They signed me for who I am and they want me to play like that, and that's why I think I went out there and all the pressure on my shoulders dropped, and that's when I started to see the best in me.

"I think there's a lot to learn from that in England."

'Mental side has been tough'

Mercer has settled back into life in England and said he feels at home at Gloucester, having made eight appearances so far.

He scored his first try in the Challenge Cup win against Edinburgh last Saturday - a competition where he tops the stats for carries made and is ranked in the top five for defenders beaten.

But, after being so open about his England ambitions and that not materialising, Mercer said he has been "struggling", especially when he spent seven weeks on the sidelines injured.

He started speaking to a sports psychologist friend again almost daily.

"The mental side of it has been really tough. I've been struggling the last couple of weeks with it," he said.

"It has been tough to come back here - not to Gloucester - but in general with the international thing.

"I don't want to be one of those guys who looks back on my career and goes 'I should have had more England caps, I should have done this'.

"That's what I worry about now."

The England omission has, however, given him clarity to concentrate fully on Gloucester, where he said fans have "not seen the best of him" yet.

The biggest learnings Mercer took from his time in France were away from the playing field.

He said living in a country away from home with a different language and culture has helped him grow as a person.

"The leadership aspect of me - around the playing group, the way I try to help the young lads and help Gloucester go forward with Skivs [George Skivington] - I feel like that's where I developed most," he said.

"Rugby-wise, I feel I was always there, but I just had that ability to enjoy it."

Results have not quite been there for Gloucester this season, especially in the Premiership - where they are on a record-breaking nine-game losing run.

In the European Challenge Cup it is a different story. The Cherry and Whites are unbeaten and facing Castres at home on Friday, knowing a win would guarantee them a home tie in the knockout rounds.

Mercer is confident a victory in the league will follow soon, given their European form.

"The results will turn for us, we will get the luck of the bounce here or there, I strongly believe in that," he said.

"If I've got a smile on my face, I'm playing the best rugby I can."