Gareth Southgate sought assurances from Sam Allardyce before calling up Ravel Morrison for the first time to his England Under-21 squad for this month's European Championship qualifiers against San Marino and Lithuania.

The midfielder, who has five caps at age groups up to the under-18s, had been highly rated at Manchester United's academy, only for the hierarchy at Old Trafford to lose patience with the youngster after a series of controversies off the pitch. Morrison narrowly escaped a prison sentence for witness intimidation in 2011 and was sold to West Ham United for £1m shortly before his 19th birthday, playing only once as they gained promotion from the Championship.

Birmingham City took him on loan last term, where his game progressed with regular senior football, and the 20-year-old has excelled in Allardyce's West Ham team when offered his chance this season. His wonderful individual goal at Tottenham Hotspur on Sunday was a fourth of the campaign and timely reward following his call-up to the Under-21s.

"We'd been very aware of him coming through the England junior teams and I've spoken to Sam at length about his progress," said Southgate. "He's in a good place, playing extremely well, with good people around him at West Ham. If you look historically with Sam, and the profile of players he's worked with, he's been very good at dealing with creative people: [JayJay] Okocha, (Youri) Djorkaeff. He's at a good club, a club that are prepared to play him in the first team.

"We'd always maintained a dialogue with United and we talk to all clubs about whether it's a good moment to pick their player. There's no point picking a player if the club feels it's not the right message to send the player at any given time, for various reasons. That's why I wanted to speak with Sam. Is this a good moment? I can see what I'm seeing on the field. I asked if it would be a positive and Sam said: 'Absolutely. He's been terrific'.

"He's a charming lad. Anyone who meets him would tell you that. How do young people learn? Unfortunately usually by making mistakes. It's what you do thereafter that's important. It's lovely to see him playing the way he is. The question is how can we make it work for him when he's with us, to make sure he's comfortable?"

Morrison joins the likes of Raheem Sterling and Wilfried Zaha, both already capped at senior level, as exciting and flamboyant talents in Southgate's party as the recently appointed under-21s manager seeks to secure two wins this month to exert some authority on qualifying Group One.

The West Ham midfielder is expected to make his debut in San Marino on Thursday, with Barnsley's on-loan goalkeeper Jack Butland to captain the side after Andre Wisdom was banned for four games following his dismissal for kicking Tim Vayrynen in the draw in Finland last month. Uefa extended the ban by a further three games after the Liverpool defender punched Dani Hatakka in the chest as he left the pitch, with the Football Association opting against appealing against the suspension.

"The one thing I said from the off was I wanted creative talents in the squad," added Southgate, who will be without his full-backs Luke Shaw and Jack Robinson through illness. "There always has to be a balance but somebody who can unlock defences – in the same way Raheem, Wilf or Jesse Lingard can – is a valuable commodity, especially in the types of games we've got where opponents are banking up against us and making it very difficult to break them down. But it's just great to see a young man like Ravel enjoying his football. He's reading lots of good things about himself, which must be great for him. That can be a self-fulfilling prophecy: it encourages you to keep doing the good things you're doing.

"The fact he's playing every week is a great leap of faith from Sam and shows how well he's playing. I've seen him a couple of times and he's been excellent in that league. This time last month only a third of our squad were playing first-team football. I think it's two-thirds from last weekend, albeit with some on loan. Like with all young players it'll be peaks and troughs over the next few weeks and months but they'll only learn by being in these situations. Young people make such massive leaps and progression at this sort of age and he's clearly doing that at the moment.

"But I'm almost refusing to talk about talent any more. I'm calling it potential because that's what we have. We have lots of players with great potential. Technical ability won't be the thing that gets them there. They're all here because they have that. It will be the other aspects: physically, psychological, social, that determine how far they all go."