The England under-20 international was part of the Young Lions' World Cup-winning squad in the summer before linking up with the Trotters for six months.

He made 23 appearances in all competitions - 16 of them from the start - and scored three goals. The 20-year-old forward was largely deployed out wide at the Macron Stadium and has returned to St. James' Park following the expiration of his loan spell.

Armstrong scored 20 goals and was selected in the League One team of the season during a loan spell with Coventry in 2015/16 and spent last season with Barnsley, scoring six times - including the Tykes' goal of the season, against Preston North End.

He is likely to head out on loan once more for the second half of the current campaign, with United keen for the player to gain more experience.