The 22-year-old centre-back, formerly of Wigan Athletic, has drawn comparisons to Manchester City’s John Stones because of his accomplished displays in the Scottish Premiership this season.
Celtic had been expected to snap him up in the January transfer window but Premier League clubs are preparing to outbid the Glasgow giants.
The Daily Mail, who report the news of the Saints scout’s mission, also claim Crystal Palace and Newcastle United have been watching Hendry.
Saints signed Virgil van Dijk from Celtic in 2015 and now look set to make an astronomical profit on the Dutchman, opening the way for the club to bring through another young central defender.
Celtic were due to speak to Dundee about Hendry after Tuesday’s game, a 2-0 victory at Dens Park, but around 18 clubs were represented in the stands, many to watch the young centre back.