The 19-year old defender, who has played three times for the Scotland U21s, was included in Gordon Strachan's 24-man squad for next month's friendly with Poland which prompted words of high praise from his club boss.
"This is brilliant news for him and for the club. Andy is still a teenager but he has already been through a lot in his career and deserves to be where he is now," McNamara, who played 33 times for Scotland, told the Scotsman.
"It is great credit to him and his family that he has gone from being told by Celtic that they didn't want him, on to amateur football with Queen's Park, signed for us and now he is in the Scotland squad.
"That speaks volume for the progress he has continued to make. I would challenge anyone who has watched us play this season to be surprised by this though. It is not a great shock because of how he has been performing week in, week out.
"So we are all really happy for him, even though there has been a bit of banter and stick for him from the other boys at training - just as you would expect!"
Robertson only joined the Tangerines from Scottish League Two outfit Queen's Park this summer but has already gone on to start in all 25 of United's league matches this season.
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