Walker scored his first England goal on his 77th appearance in Saturday's European qualifying draw with Ukraine.

"I've talked him out of [international] retirement twice, after the Euros and after the World Cup" said Southgate.

"I think he loves being here and he's wanted to keep going and now he's thinking about how many caps can he get.

"He's critical to us. If we're talking about world-class players in their position in our team then he's probably one of them.

"I think he didn't realise how much value we have for him and how important he is for us. He's probably not going to thank me for sharing that".

Walker made his England debut under Fabio Capello in 2011 but the majority of his international caps have come under Southgate since his appointment as manager in 2016.

The former Tottenham and Sheffield United defender, who could earn a 78th cap against Scotland on Tuesday, says increased competition in the full-back position prompted him to consider international retirement.

"[With] the likes of Trent [Alexander-Arnold], Tripps [Kieran Trippier], Reece James coming through, you do think your days are numbered," he said. "And how many holidays and summers that I've sacrificed. I've been doing this since I was 19 [when] I joined the senior team - I'm 33 now.

"Me and Gareth have a good relationship off the field. We do speak and I feel that I can still bring something to the team. So why stop?"