The 20-year-old arrived at Fratton Park temporarily from Manchester City in the summer.
And his immense potential has been there for all to see this season as he’s established himself as the club’s first-choice goalkeeper – making 35 appearances in all competitions to date.
As a result, his market value has already risen by £500,000 under the guidance of Danny Cowley.
But where does that shoot up in price rank across every League One loan deal ever?
Well, thanks to transfermarkt.com’s transfer values, we can find out...
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17. Bjarni Vidarsson - £900k increase
Loan club: AFC Bournemouth (2006-07) Parent club: Everton Appearances: 6 Current club: Silkeborg Picture: Ian Walton/Getty Images Photo: Ian Walton
18. Michael Chopra - £1.35m increase
Loan club: Barnsley (2004-05) Parent club: Newcastle Appearances: 42 Current club: Retired Picture: Alex Livesey/Getty Images Photo: Alex Livesey
19. Mark Wilson - £1.58m increase
Loan club: Doncaster (2004-05) Parent club: Middlesbrough Appearances: 3 Current club: Retired Picture: Jamie McDonald/Getty Images Photo: Jamie McDonald
20. Dele Alli - £2.70m increase
Loan club: MK Dons (2014-15) Parent club: Spurs Appearances: 12 Current club: Everton Picture: Shaun Botterill/Getty Images Photo: Shaun Botterill