THE Scottish independence debate may only have intermittently breached the stadiums of the Scottish Professional League but, more than 1000 miles away in Camp Nou, it was addressed loud and clear last weekend.

In a pre-planned act, a large section of Barcelona supporters chose to use a time typically reserved for their own political preferences to send a message north to Edinburgh. But why use football as a medium to communicate on a much bigger issue? To understand that, we have to understand FC Barcelona as an institution, what it means for Catalans, and the role they think Scotland can play in their future.

In July 2010 more than one million Catalans marched down Passeig de Gracia, one of Barcelona's main boulevards, and I was there to witness the spectacle. Despite being a street of significant width, the density of bodies combined with the heat was suffocating. Two items marked the uniform of the day: the Estelada (a pro-independence flag), and the FC Barcelona shirt.

On Thursday, September 11 2014, they dwarfed their previous effort. My point of observation this time was Gran Via de Les Corts Catalanes, a thoroughfare that stretches some 13km through the middle of Barcelona. As far as the eye could see there stood masses clad in red or yellow, colour co-ordinated and filed into rows to form the four red bars on a yellow background that constructs the Catalan flag - a symbol easily recognisable from FC Barcelona's second kit last season.

The same choreographed pattern was unveiled simultaneously along the 10km Avinguda Diagonal, the two lengths meeting to form one giant red and yellow 'V'. This giant letter represented the Catalan word "votar" (to vote). Around 1.8m people took part.

The cause, as in 2010, was clear. The Catalans were demanding the same right Scotland has been granted today. The referendum is being watched closely here: almost every second word on Catalan television seems to be "Escòcia". Newspapers are full of analysis; people discuss it in bars; local politicians refer to it frequently; and, as soon as someone realises you're a Scot, you know exactly what the next question will be.

Yet I would wager Catalonia's obsession with September 18 isn't widely known back in Scotland, and the Catalans themselves are aware of that. How then, could Catalonia let us know they're watching? Football answered my question.

On the 17th minute and 14th second of every FC Barcelona game at Camp Nou, supporters cry out in unison. The timing commemorates 1714, the end of the siege of Barcelona in the War of the Spanish Succession. The shout, "Independència", a deafening protest from the stands. Huge banners are unveiled simultaneously and, in Barcelona's home game against Athletic Bilbao last Saturday, text and symbols were the weapon of choice. Text directed at a very specific audience.

When the 14th second of the 17th minute arrived, not only did the chants start, but supporters in the lively south stand held up gigantic white letters. Behind them, others brought out flags, creating a colourful backdrop. The words read "Serem Lliures" ("we will be free"). The flags were not only Estelades but also Saltires.

You may ask why Catalans are so desperate for another country to vote for its independence, and why they feel the need to send that message through football? One soci (Barça's most dedicated supporters) told me Catalans hope Scotland can "show them the way" to independence. Another reaffirmed that, noting "if Scotland votes Yes and get into the EU, it will be an argument for us that can't be knocked down."

According to this soci, it is in Barcelona's DNA to support a movement like the independence campaign in Scotland. "Historically, Barça is a club bound to defending liberties", he said, "and has always been about expressing social or political differences. The first Catalan flags [during the Franco regime] were in Camp Nou around 1975/76, well before we were given autonomy. The majority of Catalan Barça fans are very sympathetic to the Scottish independence cause. We envy it."