The defender was overlooked for the March friendlies during a period when he was uncertain of starting for Chelsea – although he regained his place in the Blues line-up towards the end of the campaign.
Cahill acknowledged that being dropped came as a blow, but, after a late-season flourish, he was included in England boss Southgate’s 23-man squad to travel to Russia.
Speaking about being overlooked for international duty in the spring, he said: “I felt like (my World Cup chances) had taken a knock, missing out on that squad, especially that last squad just before you meet up was kind of a big squad to miss out on. I realised I really had to dig deep to try to perform from there until the end of the season to get myself back in the frame.
“Of course, last time I was disappointed, there was a lot going on in that time and I missed the squad. But I always had the belief that I could make the squad.”
Cahill revealed his focus in recent weeks had been on helping Chelsea to a strong end to the season, confident that it would improve his England prospects.
He said: “First and foremost, I needed to get my place at Chelsea. We had a huge end to the season with the cup final.
“That was all that was in my head, and I knew that, if I performed well, I’d be in with a shout, just like the rest of the boys who were competing for 23 places.”
Cahill, the most experienced member of England’s squad with 58 caps, said of being overlooked by club and country: “It’s very difficult and frustrating when you don’t play regularly. I’ve been lucky to do that for the majority of my career. If you’re not out there on the pitch, you can’t influence anything, and I know I’m capable of influencing it when I’m playing.”
The Chelsea captain admitted it has been a “strange season”, with the Blues finishing fifth in the Premier League 12 months after romping to the title.
Speculation has been rife that manager Antonio Conte could depart this summer and though Cahill did not clearly express his desire for the Italian to remain, he says he has enjoyed working with him.
He said: “It’s been a strange season. Obviously there’s been a lot of speculation for however many months now. (But) He’s been good for me, I’ve taken things from him, like I have the rest of the managers. I’ve enjoyed the success we’ve had together. He’s been great.”
Chelsea teenager Trevoh Chalobah trained with England yesterday morning. Defender Chalobah, 18, was invited to St George’s Park after the withdrawal of Burnley’s James Tarkowski – who was on standby for Russia.
Chalobah has not played a senior game for the Blues but has been a star performer in their youth set-up and was a member of England’s victorious under-19 side at the 2017 European Championship.
Leicester’s Harry Maguire was missing from training but he is not carrying an injury and is instead following a personalised conditioning programme.
Chalobah joined brother Nathaniel during the session, with the Watford midfielder working alongside the senior squad following an injury-hit season.
Southgate welcomed his Chelsea and Manchester United contingent back after granting them an extra week off, so Cahill, Ashley Young, Jesse Lingard, Marcus Rashford and Phil Jones were all on show.
Burnley goalkeeper Tom Heaton, who is providing back-up for Jordan Pickford, Jack Butland and clubmate Nick Pope before they head to Russia, also reported for duty.
Southgate will gather his full squad together at the weekend when Liverpool’s defeated Champions League finalists Jordan Henderson and Trent Alexander-Arnold join the squad, alongside standby midfielder Adam Lallana.