The spiky attitude, the sheer unabashed nature, has always been part of Steven Naismith.

“We’ve grown up being taught that if somebody’s giving it out hard, then don’t be scared of them,” he said during an interview in April 2006. “I’ve always played that way and a few people have been saying it’s a good thing in my game, so I don’t want to lose it.” He was a Kilmarnock player then, young, raw, impulsive, but showing the promise that led to a trial with Arsenal.

He is an integral player to Rangers now, even if Ally McCoist felt the need to substitute him during the Europa League qualifier away to Maribor last month to avoid Naismith receiving a second yellow card.

The Ibrox side went on to lose 2-1, having led the game, but the Celtic players could now talk more exasperatedly about the extent of Naismith’s influence on his team.

During last Sunday’s Old Firm encounter, he was a resounding presence: sniping, committed, unabating, so that the two strikes he sent past Fraser Forster were only the flourish to his display.

They were the first goals of his career against Celtic, yet he was irrepressible in other aspects of the game. Glenn Loovens sent him hurtling during one passage of play, much to Naismith’s fury, and he seemed to make a few choice remarks to the grounded Dutch defender as he raced past him to celebrate Kyle Lafferty’s goal minutes later.

The measure of Naismith is his refusal to be cowed, in his spirit of defiance as much as his dynamism and astute running.

He was once caught on camera mouthing a crude remark during an Old Firm game to Daniel Majstorovic, a defender who towers over Naismith. This edge is part of his feistiness.

Naismith is as likely to holler criticism to one of his team-mates as he is to an opponent, because it stems from his desire to be triumphant, but referees are also often the subject of his crankiness.

After being brought down by Biram Kayal on Sunday, Naismith leapt angrily to his feet, but to moan at the referee, Craig Thomson, rather than confront the Celtic midfielder. After another foul, Naismith inadvertently kicked his team-mate, Nikica Jelavic, in his rush to remonstrate with the official.

Georgios Samaras also received some scathing remarks after a tussle with Dorin Goian, and the sense was of Naismith being the game’s fiercest presence.

He admits that he struggled to cope with the change in culture and expectation after leaving Rugby Park for Ibrox in August 2007, and two serious injuries interrupted his progress. Yet only Allan McGregor, Steven Davis or Jelavic are as important to McCoist’s side as Naismith. He is a clever, adept footballer whose imposing attitude enables him to be a key figure.

McCoist has used him as a second striker and as a central midfielder, but he tends to be most effective from a role on the right flank. Like Scott Brown, the Celtic captain, the position is only nominal, since he drives infield, makes late runs into the penalty area and provides defensive cover.

The flexibility is a boon to Rangers, because it allows the team to be flexible. The opening goal came when he had switched positions with Lafferty, the Northern Irishman crossing; Naismith finishing emphatically.

Billy Brown worked with Naismith at Rugby Park and once likened him to Alan Smith, who broke into the Leeds United team as a striker and ended up playing in midfield for Manchester United.

He was referring to their fearless nature, but the comparison stands in the awareness and shrewdness required to play in several different positions. Craig Levein also treasures Naismith, for his attacking instincts, workrate and sense of responsibility.

He is one of a group of small, agile, nimble-footed players that the Scotland manager likes to use on the flanks, but James Morrison, Graham Dorrans, Kris Commons or Robert Snodgrass do not offer the same defensive shift.

Naismith was a player of the year nominee last season and he already looks to be building on that form again. His resourcefulness and deftness of touch inside the penalty area contributed to 15 goals last season, and he already has six to his name for Rangers this season. If Davis is the source of the team’s guile and creativity, Naismith is now established as its heart.

At Rugby Park, he cleaned Kris Boyd’s boots for a spell, after his close friend broke into the first-team ahead of him. They are both Ayrshire boys who grew up supporting Rangers before eventually playing for the club and for all Boyd’s goalscoring prowess, it is Naismith who will have the more enduring Ibrox career.

“Steven could go on to become one of the greatest players produced in Scotland,” said David McKinnon, when he was the Kilmarnock chief executive while Naismith was at Rugby Park. “I’m not reticent about saying that, because I know he’s not the type of guy who will believe his own press.” Naismith is grounded enough to have invested his Kilmarnock wages in property rather than the flash cars that are considered typical of young footballers.

In his mentality, the balance between his vehement nature and his canniness, Naismith has become indispensible for Rangers.