Williams F1 team surprised by Mercedes' advantage in 2015 testing

Although Williams ended the 2015 pre-season build-up closest to Mercedes on the timesheets - just as it had been for much of late-2014 - its best laps were achieved on supersoft tyres, whereas the champion team used softs, making Mercedes' 0.2-second advantage much greater in reality.

Asked if he had expected Mercedes to be that far ahead, Williams technical chief Symonds replied: "No, I didn't. Like most people I was quite surprised at the laptime that they did.

"I thought we had a handle on where they were up until that point and the gap was really quite similar to the end of last year, but that lap was pretty impressive I thought.

"But let's see. I certainly don't think we're in a bad position and I think maybe by the time we get to China or Bahrain we'll start to know where we are. Melbourne's always an odd circuit to try to establish the order from.

"I think we've worked hard, we've produced a good car, we certainly haven't dropped off from where we were last year and we've continued the solid progress we were making last year.

"I think that's very gratifying so eventually we've got to get up there and beat them."

Symonds also suspects that Williams could be stronger than it appeared at main test venue Barcelona, which he said "wasn't a terribly good circuit for us last year at all".

"The trouble is we look at this small sample of results, be it testing or the first race, and we always want to try and predict from that but of course you can't really do that.

"All I know is that if we continue doing what we did last year I think it's in the right direction.

"Last year we made good steady progress towards them so we were doing the right thing."

He is sure there is plenty of room for in-season development progress from Williams.

"I think there are a lot of areas where we can see the potential but haven't quite reached it yet so I'm confident we can move forward a lot," Symonds said.