Formula 1 has certainly had no shortage of tragedies over the years. Whether it be spectators watching on from the side affected or the drivers themselves, there is always a risk involved. Certain events tend to stand out, though, and it was on this day in 1975 that one of the most controversial and tragic races in the sport's history took place at Montjuic Circuit in Barcelona.

Staff had to work overnight to ensure that barriers around the track had been firmly bolted into place, after a number of F1's major players threatened to strike over safety concerns. Still not fully convinced by the makeshift work carried out, it took the threat of legal action from race organisers before drivers finally agreed to call off their planned walkout to take part in qualifying.

However, Emerson Fittipaldi, the reigning world champion, was still furious about the decision, taking part in just three laps of the Saturday session before pulling into the pits. Fittipaldi announced the next morning that he would not return to the track for the remainder of the weekend and duly returned home.

To offer another sign of just how uncomfortable and concerned the drivers felt, Ken Tyrrell emerged with a spanner to check that the barriers were exactly as they were meant to be. Hindsight tells us that he, and his fellow competitors for that matter, were right to be cautious.

When the race did eventually get underway, it was Ferrari who took command of things as Niki Lauda and Clay Regazzoni raced to the front of the pack. Lauda was soon sent spiralling out of control by Mario Andretti, seeing his race come to an abrupt end.

It was not until lap 26 when the worst fears of Fittipaldi and co came true as Rolf Stommelen lost his rear wing, which sent him crashing into the barrier that his own mechanics had spent time working on pre-race.

Carlos Pace, trying to avoid the German, who had bounced back towards the track at this stage, himself crashed, leading to one of the sport's darkest moments. Five spectators lost their lives when struck by Stommelen's car, which was sent flying, while the German himself suffered a broken leg, broken wrist and two cracked ribs.

Incredibly, the race was not halted for another four laps, in which time Jochen Mass had usurped Jacky Ickx at the top of the standings for his only ever F1 win. Third place went the way of Frenchman Jean-Pierre Jarier, although with a quarter of the race still left to go before it was suspended, only half points were awarded.

The race is also memorable for another reason, with sixth-placed Lella Lombardi becoming the first - and so far only - woman to score points at a World Championship.

On this occasion, though, points mattered very little to those taking part. The famous Monaco-esque street settings of the 1975 Spanish Grand Prix were not to be seen again, thanks to a weekend where commerce and politics overtook safety at the cost of human lives.