And McKelvey praised Blair’s ability and versatility ahead of the final showdown against England in Cork but emphasized that every member of the 26-man squad had played a significant role in the recent success.
McKelvey said: "Alex is an important player for us; he has played in three different positions and he has performed well in all three. I don’t see that being any different against England.
“But everyone has a vital role to play. That is something that we have stressed; each individual has a huge responsibility and a big role to play in this programme.
“We have done all the hard work to get ourselves into this position and we are in contention. We have won four games so far this season, but we are still looking to raise our level of performance for the next match. I am absolutely delighted with the progress the squad has made during the season. We have got all 26 players going in the right direction; especially up front."
Scotland kicked off the campaign with a convincing 25-8 win over England A at Melrose in February, but McKelvey does not believe that result will hand his side a psychological boost during the next meeting.
He added: “I don’t really think that result will have a massive bearing on the game. This group of players has played against England twice over the under-17 and under-18 programmes and they have been successful in both games. We are certainly not overawed at the prospect of facing England and everyone is focused and will perform to the best of their ability. We will find out tomorrow just how much progress we have made.”
Scotland under-18 team (sponsor Martin Currie) to play England at Musgrave Park (Tuesday 1 April, kick-off 2.30pm)
15 Sam Hughes (Merchiston Castle School)
14 Max Learmonth (Berwick)
13 Alex Blair (Edinburgh Academy)
12 Alex Dunbar (Annan)
11 Tom Brown (Edinburgh Academy)*
10 Ross Aitken (Bell Baxter/Howe of Fife)*
9 Alex Black (Prince Henry’s School)
1 Nicky Little (Hawick)*
2 Alun Walker (Musselburgh)
3 Craig Owenson (Musselburgh)*
4 Grant Gilchrist (Stirling County)
5 Robert Harley (West of Scotland)*
6 Jason Hill (Stirling County)
7 Michael Maltman (Musselburgh)
8 Stuart McInally (George Watson’s College)* CAPTAIN
Substitutes: Mungo Strachan (Fettes College), Luke Pettie (Gala Wanderers), Andrew Fraser (York), Callum Connor (Bradford Grammar), Ross Sutherland (Sandbach), Michael Fedo (Bell Baxter/Howe of Fife), Russell Weir (Merchiston Castle School), Michael Tait (Kelso Quins)*, Jamie Harris (Merchiston Castle School), Seumas MacKenzie (Murrayfield Wanderers), Rory Drummond (Bell Baxter HS), Jamie Harris (Merchiston Castle School)
*Member of Scottish Rugby’s National Junior Academy and supported by Area Institute of Sport.