Gunn is the son of Norwich City goalkeeper Bryan Gunn, and the 22-year-old spent last season on loan at the Canaries - the club he was at as a youth player - keeping 16 clean sheets for the club in the Championship.
Gunn was called up to the England national team by Gareth Southgate for his side’s 2018 FIFA World Cup pre-tournament training camp.
The 6 ft 5 in goalkeeper has represented England from U-16 level upwards, featuring in the squad which won the 2016 Toulon Tournament. Gunn was then called up to the England senior side in November 2017 for a friendly match against Brazil following an injury to Stoke City stopper Jack Butland.
Given the experience he has already gathered as a young goalkeeper, Hughes is understandably optimistic of both the potential and current abilities of his new man.
Hughes said: “Angus is a player who clearly possesses a tremendous amount of potential, but his performances for Norwich and for the England Under-21 team also demonstrate the capabilities he already has right now.
“We believe he has all the credentials to become a full international goalkeeper for England in the future, and that’s exactly the sort of talent we want to have here at Southampton.
“He represents another excellent addition, and we are excited about what he brings to the squad and the further progression we feel he can make with us.
“There was a lot of interest from other teams in the Premier League, so for Angus to choose Southampton as the best option for him is another positive indication of the work the club is doing and what is being built here.”