Matt Rush scored his 50th goal for all teams since the start of the 2018/19 season to give Blues the lead after just twelve minutes, and an Eren Kinali header doubled the advantage eight minutes later. Harry Phillips scored an exquisite free-kick midway through the second half to render a Ricky-Jade Jones goal for Peterborough a mere consolation.

Posh fielded a young side, but Fagan thought his team coped with the intricacies of a different type of 4-4-2 formation to earn their success: “I thought we performed well,” he said. “Their shape causes a problem because they play a diamond in midfield, and they are renowned here for having good, talented lads that can play football.”

“I thought defensively we stuck to a game-plan and we had done video-analysis of the opposition, so that helped us. I drummed it into the lads that they had to work for each other and stay in our shape and it worked perfectly for us as we managed to score two early goals.”

“I wanted us to stay narrow because of that diamond in midfield. I wanted us to get more bodies in between so that they couldn’t play and I wanted to force them wide. I might annoy the lads sometimes with the way that I shout things at them and drive them on, but I’m going to keep doing it because I want them to get better, because that’s the most important thing. If they hate me, it’s not a problem as long as they are improving.”

Southend’s own team had little senior experience of its own, and Blues almost fell behind in the second minute when Jones was given the opportunity to pick his spot from 25 yards out and he curled against the crossbar with Harry Seaden motionless.

However, Emile Acquah’s through-ball almost found Terrell Egbri in the fifth minute – Posh goalkeeper Aaron Chapman advancing swiftly off his line to snuff out he danger – and when the towering front-man put Chapman under pressure shortly afterwards, he was out of position. Kinali passed to Rush and the in-form forward did the rest, sweeping an excellent lob over the custodian and into the empty net.

“It was a great finish from Rushy, and Emile worked hard to create it,” declared Fagan. “I think that’s what the lads need to understand; to get in the first-team, the first thing you need to do is work hard without the ball, and it’s not one or two individuals, it needs the whole, collective team. Even the lads that come on off the bench, they’ve all got to have that mindset that to play football you’ve got to run around, and they’ve done that.

Seven minutes later Rush almost doubled his personal tally when Acquah laid Ide Osimeh’s pass into his path on the edge of the ‘D’. A first-time strike was turned around the left-hand post by Chapman, but Blues did manage to extend their advantage from the ensuing corner. Phillips sent an inswinging delivery to the near post and Kinali, who made his first-team debut last week, rose highest to power home a close-range header.

Blues were playing with confidence, and Phillips almost caught Chapman out with a nonchalant strike delivered with the outside of his right foot. The gloveman backpedalled quickly to save, and Peterborough immediately went up the other end where a triallist nodded a right-wing cross into the side-netting.

Rhys Bennett also planted a header marginally the wrong side of the right-hand post just after the half-hour mark for the hosts, but Southend were organised well and they could have notched a third goal before the half-time interval when Kinali and Rush combined on the edge of the box to set up O’Shane Stewart, who dragged his effort narrowly wide of the left-hand upright.

Seaden made a smart stop from Jones at the start of the second period, and a triallist also headed just wide as Peterborough began to take advantage of the benefits of playing with the wind. Rush and Acquah were both flagged offside by the assistant referee in the first 25 minutes of the half, but Blues had little to show for their endeavours until the final quarter of the match.

At the stage, they were awarded a free-kick 25 yards from goal. Positioned to the left of the goal, the set-piece favoured a right-footed strike, and Phillips took precedence over fellow dead-ball specialist Tom Clifford as a result. The stylish midfielder curled majestically into the top left-hand corner of the net and Blues were now three goals clear.

Southend pressed on, and Rush could’ve added a fourth goal with a quarter-oi-an-hour remaining when Acquah was presented with the ball by Chapman’s clearance into a defender. Acquah squared unselfishly to Rush, but his attempt from ten yards out was diverted wide by the goalkeeper’s legs. Sixty seconds later Rush teed up Egbri on the edge of the penalty area, but Chapman saved a curling shot above his head.

On 78 minutes, Peterborough reduced the arrears. Osimeh, playing at centre-back rather than in his preferred left-back role, underhit a back-pass towards Seaden and Jones seized on the opportunity to steal in and slot the ball into the bottom left-hand corner.

Any thoughts that Blues might be anxious about a home comeback were quashed by Egbri, who sent a deflected strike into the side-netting before substitute Freddy Eastwood twice went close. First, he drilled a shot through a crowded penalty area, forcing Chapman to tumble to his left to turn the ball wide, and then he met Clifford’s corner with a downward header that dropped wide of the left-hand post.

Nonetheless, the job was done for Fagan’s charges, who made it four wins from four in the league. The coach had particular praise for those players returning to the U23s fold: “I’ve spoken about people’s attitudes before, going up and coming back down and, so far, I haven’t had a problem. When they go and play for the first-team they are doing things properly, but then when they come back down they still have the same attitude and do things correctly.”

“They have given 100% and probably a little bit more than the other lads, which is good to see. At the moment it shows there is a bit of a pathway for those three [Acquah, Rush and Kinali] and also the lads that have been up in that environment before. I think it’s important for the club that lads do go up and are involved with the first-team, and it has been good to see that lads have got their chance,” he concluded.

Southend United U23s: Harry Seaden, Rob Howard, Tom Clifford, O’Shane Stewart (Freddy Eastwood, 83), Ide Osimeh, Miles Mitchell-Nelson, Terrell Egbri, Harry Phillips, Emile Acquah, Matt Rush (Henry Burnett, 83), Eren Kinali. Unused substitutes: Callum Taylor, Jimmy Wallace, Tommy Lambourne

Goals: Rush (12), Kinali (20), Phillips (69).

Cautioned: Howard (90+2, foul tackle).