The question became increasingly inevitable, the answer delivered a little sheepishly.

Scott McGleish was born in Camden, north London, Arsenal country. He grew up in Highgate, north London, Arsenal country. He lives next door to Arsenal's training ground. Both his sons support Arsenal. So who, Scott, do you support? "Arsenal's my team," he admits and grins.

Tomorrow afternoon when McGleish walks up the tunnel at Brisbane Road, ahead of him will be his eldest son, Jack, one of the mascots. Father and son will both have Leyton Orient shirts on with the No 9 and "McGleish" on the back, but there the loyalties will divide.

"When the draw was made," says McGleish, "we were at a christening and I ran in and told Jack and Harry [his youngest son]. They were so excited then Jack turned round to me and said 'I don't know who to support'. I told him if they're your team, you have to support them. His bedroom is decked out all Arsenal. Fabregas and Van Persie are his favourite players – guess what shirt I've got to try and get."

At 37, McGleish will be the oldest player on the pitch, old enough to be Jack Wilshere's father. "Being the senior player here by quite a bit, I'm called daddy, grandad, everything," he says. This is his 17th season plying his trade in the Football League. A career that begun at Charlton has taken in Orient, three times, Peterborough, Colchester, twice, Cambridge United, Barnet, two spells at Northampton and one at Wycombe. It adds up to 739 games, and 234 goals – he is three short of 200 league goals – add striking credibility to his durability. This, though, will be his first game against Arsenal.

"I live literally round the corner from the Arsenal training ground," says McGleish. "I drive past it everyday when I come into Orient. I've known Vic Akers [the Arsenal kitman] a long, long time. He's given us a signed shirt to auction off to raise money for [my sons'] school. I phone Vic now and again and go into the training ground. It's beautiful. You would have no qualms about going into train there everyday."

The surroundings McGleish works in are rather more modest, but he has already enjoyed a memorable Cup campaign, and one for which Orient, and their chairman Barry Hearn, are extremely grateful.

Tomorrow's tie, in front of a 9,300 full house and live on television, will enable the League One club to break even this season. When they were trailing Droylsden in a second-round replay with a minute to go and down to 10 men, that looked a slim prospect, but a last-minute equaliser earned extra-time during which McGleish, who had scored the equaliser in the first game, dispatched the Blue Square North side with a hat-trick. The game finished 8-2 and nine-a-side after each had two players sent off. A third-round victory at Norwich and another rewarding fourth-round trip to Swansea earned the prize draw.

"We'll do our best to ruffle their feathers," says McGleish of Arsenal. "If we stay in the game we've shown lately we've got the spirit to do it."

There are two older strikers in the League – Brentford's player-manager Nicky Forster, also 37 and Steve Fletcher of Bournemouth, who is 38 – and McGleish aims to play on for another couple of seasons. When the end finally comes he is keen to stay in the game. He is on the PFA management committee alongside the likes of Clarke Carlisle and Phil Neville, and has coaching ambitions too. At the moment they are restricted to his son's primary school team, but his willingness to give something back to a sport that has treated him well, as well as his awareness of the club's place in the community – something that is threatened with West Ham United due to move into the Olympic Stadium next door – leave a telling impression.

"I'm my little boy's primary school team manager – in my third year now," says McGleish. "I love doing it. We train every Thursday afternoon and do coaching sessions as an after-school club on Tuesdays and Wednesdays. I get a lot of enjoyment out of it. The boys go out there and just play. They show no fear and that's what we've got to do against Arsenal."

After Barça...Orient

With six goals in six games for Orient in cup competitions this season, Scott McGleish has a better strike-rate than Lionel Messi in the Champions League. Are there any more surprises lurking for Arsenal at Brisbane Road?

*Jimmy Smith is the O’s goal threat from midfield, as Norwich and Swansea both found to their peril in previous rounds.

*A winner of the FA Youth Cup with Arsenal in 2001, Ben Chorley is their Carles Puyol at the back.

*Alex Revell leads the line well for the O’s and like David Villa on Wednesday, will linger on the shoulder of the last defender.

*Recently borrowed from Spurs, Harry Kane has come off the bench to score three goals in five games. Itching for a chance against Arsenal.