I've been wondering about the inclusion of Eli Campbell, who I expected to travel for the Summer Series but didn't, and especially Tyler Onyango, who is supposed to be out of contract but not only is still around without a contract announcement, but actually did travel and play in the Summer Series and continues to make the bench for the senior squad. He's just within the cutoff to be counted as a U21, but he seems to be, at least for now, a fringe first team player.
Both Campbell and Onyango have had loan spells in League One, and considering they're in and around the senior squad and made the bench today, I'd expect to see them. They're both versatile and I'd love to see them given a chance and prove their worth.