That seemed to incite several Slough players, who lost their discipline and failed to grasp that he was having nothing of any dissent. Hendon on the other hand were keeping cool — helped by the fact that most of the decisions went their way.
Surprisingly, there was no place in the starting line-up for strikers Andrew Deaner, Bryan Hammatt or David Adekola as Rebels boss Graham Roberts chose to play midfielder Mark Hall and winger Youness Nabil in a makeshift attack.
Hendon made most of the early running and almost caught Slough short at the back when Al-James Hannigan was taken off the field for treatment to a head wound picked up just minutes into the match. Paul Whitmarsh, a striker targeted by Roberts during pre-season, hit a good chance well wide after nine minutes. And, a minute later, Rebels goalkeeper Danny Honey pulled off a great reflex save to stop Whitmarsh's powerful half-volley and then did well to save the rebound.
Slough failed to create anything up front and were reduced to long range efforts, one from Micky Engwell which flew just over from 30-yards out. But, on the half hour mark, tempers flared and the game flew out of control. First, Hawthorne was warned by the referee after clashing with a Hendon player resulting in the two players squaring up to each other.
Then minutes later Hawthorne was booked for kicking the ball away, although he protested to the referee that he was merely taking what he thought was a Slough free-kick. Leon Townley led by example at the back for Slough, keeping his head throughout the match, and it was his superb tackle that stopped Marvyn Watson from getting a shot on target in a dangerous position on 32 minutes.
The killer blow arrived on 34 minutes as Hawthorne was shown a second yellow card for his reckless challenge on Whitmarsh on the edge of the box. And, to rub salt into Slough's wounds, the talented Freddie Hyatt hit a pin-point free-kick past the rooted Honey that Manchester United star David Beckham would have been proud of. The temperature was raised. A few minutes later, Mark Pye, not known for his shyness, spoke too loudly about another decision and went in the book.
The goal prompted Roberts to revert to a flat back four and he pushed Hannigan up front in a bid to win the aerial battle in attack. Then as the referee denied Hall a decision after he was grounded by a tackle from behind, the ball ran to an opponent and Pye came crashing in with a late challenge. That got him his second yellow and his marching orders. Further tense moments and barracking of the officials followed as half time approached and at the whistle the referee went off to the worst booing heard at the ground for some time. Clashes had continued on the half-time whistle as Hannigan clashed with Hendon officials.
Graham Roberts rearranged his nine men to put defender Al-James Hannigan up front, with three in midfield and a back four. Slough settled and started to produce a controlled fightback, with Nabil making raids. On one, he got into the box, crossed over to Eddie Denton (on for Hall) who found Hannigan clear on the left, but he only headed tamely at the keeper as he appeared to slip.
Honey was again called in to action to thwart Whitmarsh after he was let in by a Townley error and the Hendon striker headed wide soon after from a great cross from Jon Daly. Nabil had a speculative effort go straight into the keepers arms on the hour and another flash inches wide from 35 yards, which was the best chance for the home side.
After an hour, though, Hendon were making use of the space and giving Slough more of a run around, and on 71 minutes Roberts had to try more attacking options and he brought on strikers Bryan Hammatt and Andrew Deaner for defenders Timothy and Daly.
But they could make little impact as Hendon kept the pressure more and more on Slough's defence, marshalled well by Leon Townley. With Slough trying desperately to get back on terms they had to throw men forward which left room for Hendon on the break.
And after several threats, the visitors finally struck the killer blow when the speedy Marvin Watson broke quickly to run upfield and found Dominic Gentle clear on the left. He stepped inside and drove the ball home, to end a miserable day for Slough
There was even a chance to see former Bulgarian international striker Bontcho Guentchev, who graced the Wexham Park turf for the final 10 minutes, on a day that won't stick in the found memories of Slough Town supporters.
Mark McGhee, who was spotted by Rebels fans at Wexham Park on Saturday, says he has not ruled out the possibility of managing a non-league club. But former Wolverhampton Wanderers manager McGhee, who has applied for the vacant managerial post at Reading, confirmed that he was merely an interested observer at Slough's FA Trophy clash with Hendon.
Despite openly admitting he would like another shot at managing the Royals, McGhee is unlikely to be given the chance, as Reading chairman John Madejski does not appear to be willing to consider his application after McGhee's acrimonious departure at the end of his last reign as Royals' manager.
But, although he is still looking for a route back into management, says he was not at Wexham Park to consider a return via the non-league door. "I would never rule anything out, but it's not even been in my thoughts and I've not given it any consideration," said McGhee. "That's not the reason I was at Slough. My son was due to be playing for Woking Reserves, but he didn't end up playing for them, so I decided to go to Slough." McGhee is a friend of Slough striker Andrew Deaner's father.
Hendon Line up
Gary McCann, John-Simon White, Simon Clarke, Jon Daly, Paul Towler, Gary Fitzgerald, Steve Baker, Freddie Hyatt, Paul Whitmarsh, Marvyn Watson, Dominic Gentle. Subs: Curtis Warmington (for Fitzgerald), Jason McKoy, Bontcho Guentchev (for Gentle), Dale Binns (for Baker), Steve O'Carroll