Six races into Williams' abysmal 2019 campaign, there is finally "light at the end of the tunnel".

That is the claim of team boss Claire Williams, even though George Russell and Robert Kubica are still easily dead last at every grand prix.

But both she and former team driver Sergey Sirotkin said they saw the serious lack of performance coming.

"I don't want to say too much, but around the middle of last season it was clear that our problems were very deep," Russian Sirotkin told the Match TV correspondent Alexey Popov.

"We realised then that the solution to the problems would not be one or two updates. First of all, it was a complete reworking of the structure and processes in how the car should be built," he added.

Interestingly, Claire Williams does not disagree with that.

"You say it wasn't the start to the season that we envisaged, but I think we anticipated what was coming," she said.

"I definitely feel that we can see some light at the end of the tunnel now and I think probably just from the time sheets and the last races we demonstrated that we are closing that gap.

"It may be slow but we all know that it takes time to bring performance to your car," said Williams.

The once-great team is currently preparing a mid-season upgrade that it hopes will either be the direction for the future, or indicate that a return to an older car concept is necessary.

"There's definitely a lot of good work going on back at the factory that people may not necessarily be seeing yet," Claire confirmed.

"The aero team are doing a great job finding performance in the tunnel and we're going to be bringing that to races over the coming weeks and months. We have a package coming mid-way through the season that we hope will bring some significant performance to us."