McLaren team principal Martin Whitmarsh has admitted he made the call to keep Lewis Hamilton out on track during qualifying at the Spanish Grand Prix despite suspecting the car might run too low on fuel.

14660 - Whitmarsh explains McLaren's qualifying blunder

Hamilton was excluded from the qualifying results after the stewards discovered that he had been insufficiently fuelled to make it back to the pits under his own power and provide the mandatory one-litre fuel sample. He started from the back of the grid as a result and, despite a strong drive through the field, only picked up four points for finishing eighth.

McLaren first suspected he was short fuelled on his out lap from the pits and had the opportunity to avoid a penalty by calling him back into the pits, but Whitmarsh said he had to make a tough call to keep him out on track.

"I put my hand up," he said on Sunday. "People assume that you have an empty vessel that is a fuel tank and you just throw the fuel in, but it's much more complex than that. You look into the tank and you can't see anything other than baffles, pumps, collectors and all sorts of complexity because you're trying to get the last few grams of fuel being thrown around in a relatively empty vessel at four or five Gs. So it isn't straight forward, but the mistake was made.

"We didn't know exactly what had happened, frankly. The data told us we had less fuel in there than we would have liked and we didn't know whether the data was right or wrong. You then have to take a view and I took the view that I wanted to give Lewis the opportunity to be on pole. I believed he could be on pole and I think that was good for him. We then continued to assess it and took the decision that we knew we had to provide one litre of fuel, that's a definitive regulation and we knew we would be sampled, so we decided that we'd make sure we complied and we got 1.3 litres out of the car and we took that decision.

"I don't think we, rightly or wrongly, envisaged the severity of the penalty that resulted and also Formula One is a great one for hindsight and there's a lot of analysis from experts to inform you where you got it wrong. But I put my hand up, and as team principal as that was unfolding - bearing in mind you're in the adrenaline fused seconds of it, you're trying to understand what's happening and you've got 10 or 20 people trying to deal with it - I said let's go for it and once we get over the line let's start to monitor.

"It's not easy [to monitor], you can't just put a dipstick in and find out how much fuel's there, it's a very complex system, and we could have stopped the car and taken three or four litres out of it and I would have been very embarrassed. I was still pretty embarrassed and that's the challenge and you've got to take those decisions."

Whitmarsh said he was hugely impressed with the way Hamilton dealt with the team's error and, while he was surprised by the stewards' penalty, he and the team fully accepted the verdict.

"I wanted to give Lewis the opportunity to be on pole, I think he was capable of doing that and of course he was. I did not expect what happened in the way of the penalty, given that the black and white regulation is being able to give the sample and we could give the sample. But I'm not commenting on what happened with the stewards because it's a fruitless task. There's no point in me making observations on it. They made a decision and we got on and raced with it.

"I think Lewis was extraordinary on Saturday night, I was talking to him on a number of occasions, and I'm so proud of the level of maturity he brought to bear on dealing with the frustration and the support that he showed for the team and myself. I'm very grateful for that.

"But I sensed then that he would have the control, the balance and the maturity to deal with what was a very difficult race in the right way. A two-stop [strategy] was always going to be a challenge and he did it fantastically and he made the best out of it, got some points and that's what this championship is about, it's just collecting those valuable points. A great disciplined drive from him."