The Deans stormed to a club record away Wessex League Premier Division win at Cowes Sports.
Zak Willett took his seasonal goal tally to 19 with a hat-trick while Connor Duffin now has 17 to his name after a double strike on the Isle of Wight. Both have netted 16 times in 14 league starts.
Harry Jackson replaced Willett just before the hour mark and promptly scored twice in 10 minutes.
Liam Kimber had opened the scoring on 16 minutes and Ben Anderson completed the rout on 76 against a Cowes side who had only lost one of their opening six home league matches.
It was Horndean’s fifth successive away league victory and they remain the only side in the Wessex Premier with a 100 per cent record on their travels.
Incredibly, Birmingham’s side had already recorded two similar scorelines previously this term - against Christchurch in the league and Hamble Club in the FA Vase.
‘We played some really, really good stuff,’ said the manager. ‘Going over there we had to be professional in our approach and our attitude had to spot on.
‘The boys know what I demand, but now they are starting to demand it of each other.
‘I never want us to be comfortable - that’s a scary word in football.
‘I said beforehand we had to get the three points – I didn’t care if it was 1-0 or 9-0, it’s still three points.’
Horndean have been ultra impressive at both ends of the pitch in Wessex action. Not only have they scored the most goals - 51, one more than Fareham - they also boast the division’s best defensive record.
Former Baffins and Portchester keeper Cameron Scott has only conceded seven goals in 14 league games. The shut-out at Cowes was his eighth clean sheet during that time and only once has he conceded more than one goal in a game - in a 2-0 home loss to Stoneham, Horndean’s sole league defeat, on September 4.
Birmingham credits ex-Baffins boss Leigh for his work on the training ground in turning Deans into such a hard side to score against.
Asked if that work has improved the defensive record, Birmingham replied: ‘One hundred per cent.
‘We work a lot on the defensive shape without trying to take away from our attacking shape.
‘Steve’s a good, good football man, I’ve known him a long time and it was a no-brainer to bring him in (during last season).
‘He’s been outstanding - he’s old school, but I don’t think there’s enough old school in the game at the moment.
‘If you think about it, if you score a goal you’re not guaranteed to get any points. But if you keep a clean sheet you’re guaranteed at least one.
‘Jocko (Scott) has been absolutely phenomenal but so have the four in front of him and the midfield two as well. That’s credit to the work Steve’s done on the shape.’