The 24-year-old clinched a £12million move to Aston Villa yesterday despite facing months on the sidelines as he recovers from foot surgery.

However, Southgate knew the writing was on the wall as the midfielder grew increasingly unsettled, ultimately handing in a transfer request which was rejected in January as Tottenham once again set their sights on him.

Southgate told BBC Radio Tees: "We have felt for quite a while now that it was going to be very difficult to hang on to Stewart beyond the end of last season whichever division we had been in.

"He had expressed a desire to move on and I am pleased for him he has got the move.

"It's a good deal for us and Aston Villa have got a player that Martin had coveted for a while.

"We wish him well and I hope it works out for him."

Southgate was Boro captain when Downing emerged from the Academy to force his way into the first team, and retains a great affection for the homegrown talent.

However, he knows too how important the proceeds of his sale could be to the club in the wake of relegation from the Barclays Premier League.

The manager said: "He is a genuine kid. He has progressed a lot in his time with us.

"I can remember him coming in for his debut and playing with him and I have enjoyed working with him. He's a talent.

"All players need a new challenge at some point, and there's no hiding from the fact that the money for us at this time is important as well.

"We have got to move forward as a football club."

Whether or not Southgate is able to re-invest that cash, however, will come down to chairman Steve Gibson and chief executive Keith Lamb.

He said: "I can't answer that, that's for Keith and Steve to answer. All I can say is it was a deal that was acceptable for us."

Boro have already made two summer signings, one of them Colchester winger Mark Yeates, who along with England Under-21 international Adam Johnson, will be asked to provide the width in the Coca-Cola Championship.

Southgate said: "We have got a couple of good wide players in those two and we are going to need goals from those areas of the field - that was a big disappointment for us last year, that we didn't get that.

"For us to achieve what we want to this season, that's going to be crucial."