NATIONALITY is such a fluid concept these days but that doesn't stop people getting fairly worked up about it whenever it infiltrates the sporting landscape.

The relative ease and affordability of travel, the opening up of previously closed borders, the shifting geographical landscape, and the rise of those seeking asylum from impoverished or war-torn countries have all combined to produce a transient culture where few stay in the same village, town or city for the entirety of their days.

It has led to a necessary softening of the rules when it comes to international football. Where before a player could represent only the country of his birth, there is now an array of options for those with well-travelled forefathers or a sense of wanderlust themselves. Naturally these new guidelines are open to abuse, with many countries - but not the British home nations - taking advantage of residency rules to offer passports and then a pathway into international football for any talented player who just happens to stumble across their border. Family trees have also been studied like never before, international associations poring over page after page of historical documents to see if a parent or grandparent's birthplace can open up another avenue for a coveted player.

It is the most pragmatic approach to ensure an international side remains competitive but it is not a mindset often shared by that nation's more fervent supporters who, with heart leading their head, would prefer to see 11 players all speaking with the same local accent pulling on the shirt.

Defectors tend to get a hard time. The jeering of Aiden McGeady on Friday night by Scotland fans, unhappy at the winger's decision to turn out for the Republic of Ireland, was evidence of that, as was the whistling that met every touch by Diego Costa, the Brazil-born naturalised Spaniard, during the recent World Cup finals. It can often lead to a moment of awkwardness whenever the country a player chooses to represent comes up against the land of his birth. Russell Martin, however, diplomatically and diligently tiptoed his way through the minefield.

Born and raised in Brighton, Martin was never likely to be considered for an England cap. A Scottish father, though, did provide a secondary option and the Norwich City defender grasped at it willingly. First under Craig Levein and now Gordon Strachan, he has gone on to become a steady and reliable performer at the heart of a defence that has amassed an impressive number of clean sheets.

Martin comes across as articulate and affable in interviews, and he is shrewd with it. Asked to recall his memories of Scotland versus England games, ahead of the sides' meeting at Celtic Park tomorrow, and his brain suddenly goes a bit hazy. There is a sheepish smile there, too. There is every likelihood he cheered when Paul Gascoigne broke Scottish hearts at Euro 1996, and celebrated when Paul Scholes scored his double at Hampden in 1999.

He is not, of course, going to mention that to a Tartan Army who have warmed to his whole-hearted approach to defending, nor is he going to patronise them by claiming that as a young lad in Brighton he used to stroll around singing Flower of Scotland. The only sensible approach, then, is to leave the past in the past. "I remember Euro 96 and stuff like that and then the Euro 2000 play-off when [Don] Hutchison scored," he said. "But my memory isn't the best, it's a bit hazy."

He can, of course, remember the most recent time these two rivals met, a game that removed any remaining doubts regarding Martin's football loyalties. He was part of the Scotland team that went to Wembley last August and gave the English a real fright before ending up - perhaps unfairly - on the wrong end of a 3-2 scoreline. It is one of the few Scotland fixtures that Martin looks back on with regret. "We probably owe them one now," he added. "We should have got a result there and we were disappointed not to. That is probably the result - along with Germany - that rankles most with myself, but the rest of the lads and the manager as well.

"We definitely should have got a result. Losing goals from set-plays was annoying. Ricky Lambert had a free header from inside the box. We were not organised enough. He'd just come on as a sub, and they scored form that, which was disappointing.

"But we are a different team now. We are a long way down the line, further in the manager's tenure, and a different team. They will come up here and they will know they are in a tough game."

It is Scotland's final game of 2014 and they approach it in good spirits, their promising start to the Euro 2016 qualifying campaign pushed on a notch by Friday's win over the Republic of Ireland.

"After Friday we don't want to end on a downer on Tuesday," added Martin. "We want to finish the job off and take us into the New Year in a good way, with Scotland in a great position to qualify from our group. "I think last time at Wembley England were surprised by how well we played, and how much we had a go. They probably expected us to sit and defend all game but we don't do that under this manager. We're a different team now to what we were then and with the momentum and belief we have in the squad now, we will give anyone a good game.