The Deans continued preparations for the new season with an impressive 4-3 friendly triumph over two divisions higher Southern League Premier South Gosport Borough at Five Heads Park last night.
That followed a 2-1 victory against one division higher Chichester City at the weekend and a 4-2 win on the road at Selsey prior to that.
But rather than focusing on results in pre-season, Birmingham is taking comfort from the improved fitness levels and football on display from his side.
Predicted Portsmouth XI v Cheltenham: changes expected to side that beat Cardiff so handsomely - but attacking duo could keep places and defender set to return
Portsmouth transfer news: Blues youngsters attracting interest but Danny Cowley has no desire to cash in just yet
Portsmouth boss Danny Cowley makes transfer admission as former Luton and Millwall midfielder edges closer to Fratton Park exit
Former Portsmouth keeper Alex Bass suffers tough night on and off the pitch as he makes Sunderland debut following Fratton Park exit
League One latest: Oxford land former Pompey striker target from Swansea as Sheffield Wednesday bemoan exciting duo's move to Brentford and former Peterborough boss criticises club
And that continued as they twice battled from behind to defeat Shaun Gale's Gosport.
Birmingham said: 'It’s been a pleasing past three games. We went to Selsey and things we’ve started to work on, we showed big improvements. The way we wanted to play football started to come out.
‘We then played Chichester on Saturday and exactly the same as Chichester, we both had a few players missing, and in 4,000 degrees of heat I thought both teams tried to play the right way and were an absolute credit.
'It was a very tough game against a very good Chichester side and they’re going to be a very good side again this year.
‘We played Gosport yesterday and we played ever so well as well.
‘The good thing about it was the work rate was there, the organisation.
‘We started to be a bit more vocal to each other - still not as vocal as what I’d like, but you’ve got to remember I’ve still got two 16-year-olds and an 18-year-old playing in the side.
‘Again, Gosport brought down a strong side, very competitive, which you’d expect Gosport to be.'
Summer signing Zak Willett cancelled out Rory Williams’ early opener before Dan Wooden restored Boro's advantage before the interval.
A brilliant second-half showing saw the Deans eventually run out 4-3 victors with Willett netting again and fellow strikers Harry Jackson and Connor Duffin also scoring.
Yet Birmingam says it's more the performance rather than the result in which he'll take greatest satisfaction from.
He said: ‘Let’s not take nothing away from us, we did do very well, and it was a fair result that Horndean won.
‘It’s very easy for the likes of Horndean to get motivated against a team from two leagues above because if you don’t get motivated you’re going to get hurt.
‘When Rory Williams put them ahead after five minutes I was thinking, ‘here we go’; it wasn’t a great start but that’s the sort of quality they’ve got on show.
‘Credit to my boys, they really dug in deep, we played some really good stuff in tight areas and got out.
‘I was happy with our fitness levels, I thought our fitness levels were very good.'
Horndean lift the curtain on their 2021/22 Wessex League Premier Division season with a home game against Alresford on Tuesday, August 3.
The following Saturday they have a mouthwatering FA Cup extra preliminary round tie at Wessex League rivals AFC Portchester.