Why Button and Williams need each other

If Williams is serious about becoming a top team again, signing Jenson Button for next season would be an emphatic statement of intent.

With Kimi Raikkonen now confirmed at Ferrari for 2017, Red Bull all tied up and Mercedes almost certain to re-sign Nico Rosberg, Williams finds itself in the enviable position of holding the most desirable seats on the grid.

It marks a distinct change to 2014, when the team was limited in who it could get after a disappointing run of form. It kept faith in emerging talent Valtteri Bottas and signed the experienced Felipe Massa as it began the rebuilding process.

Since then, third place in the constructors' championship two years on the bounce with only the fifth biggest budget is an impressive achievement, even if it has slipped to fourth this year.

But making that next step requires a bold move and bringing in a world champion who has the experience and consistency - as well as the motivation even in his mid-30s - would be exactly that.

Technical chief Pat Symonds has said Williams was not ready for a megastar such as Fernando Alonso, even if one was available. Instead, he would rather focus resources on the performance of the car.

He's right. A plug-in-and-play signing like the Spaniard, capable of winning but also expecting to fight for the title is not what Williams needs. But the decision to not spend more money on drivers needs to be reconsidered.

A study by one rival team into the contribution to results by chassis and driver found the latter to be around 15% of the competitive equation.

The resources of a midfield or backmarker team are therefore better spent on the car. But for a top team, where finer margins make the difference, it's the driver that matters.

Williams has pretentions of being a top team and winning races, so it needs to start shifting its focus. A move for Button is a logical step in that direction.

As an independent team, Williams does need to keep a tight control on its budget, but in recent years it has proved that it is capable of doing so while extracting good performance.

Button will cost more money than Bottas or Massa are currently commanding, but diverting a few million in that direction would be justified.

A signing of that magnitude will send out a signal that the last two years were no fluke and that Williams intends to fight at the front for the foreseeable future.

It will galvanise the outfit's employees, who will know that Button make the most of what they give him, while providing valuable feedback for development.

A world champion British driver in a British team will no doubt open up potential sponsorship avenues that could help offset the cost of securing such a signing. After all, Button is one of the strongest driver commodities in F1, commercially.

Should Williams sign Button, the circumstances in which it does so are important.

If McLaren makes the decision for him, Williams must be confident Button is sufficiently motivated and not simply signing up for one last pay day.

But from his mood in the paddock and public comments, it appears he still loves F1 and the hunger to compete and win remains. And his performances suggest he is still fighting.

For Button to choose to leave McLaren, Williams must convince him that it is a project worth investing in.

Its form of late has been disappointing and it has been hurt by Red Bull's resurgence, leaving it fourth in the constructors' championship.

Force India, on a very similar budget, is hunting it down as it makes the most of its major upgrade package introduced at Barcelona. But Williams is putting heavy focus into next year, with Rob Smedley having already said the 2017 aero rules change offer a "great opportunity" for the team.

Williams has proved it can make the most of a meagre budget and, aside from a huge winter turnaround from McLaren-Honda, the Grove team arguably offers Button a better chance of returning to the podium sooner.

Button is highly rated by those inside Williams and would therefore arrive at an outfit where he will receive huge support. He would be expected to lead the team but that is something he would no doubt relish.

Time is running out for Button to stand on the podium once again and enjoy success - he hasn't won a race since 2012 - and Williams offers a genuine chance of that next term.

As for the other seat at Williams, Bottas looks set to keep his drive for another season and that would be a smart move for both sides.

The Finn is believed to have been interested in exploring options elsewhere, but, with doors at bigger teams shut, Williams now represents his best option for next year.

Williams is understood to have an option on Bottas. Should it be activated, a salary rise kicks in. Given finishing third in the constructors' championship for a third year will be a tall order in 2016, a reduction in prize money is set to follow that will affect the team's overall budget.

Williams has also admitted to being affected by Brexit - as it pays for its engines in Euros, they are now more expensive because of the weak pound. This means the team is likely look to renegotiate Bottas's salary, especially if it signs Button. But that would probably mean a longer contract would need to be offered by way of a trade-off.

Bottas remains highly rated within Williams, but he hasn't kicked on as much as expected this season and, with limited options for seats elsewhere, that could hurt his negotiating position.

Where does all this leave Massa? When the Brazilian signed for Williams, it was a marriage of convenience.

Massa wanted a team where he could realistically get some results but his stock was low. Williams was at the start of a rebuild and needed experience and Massa was the best it could get at the time.

He has done a solid job since, and talks have begun regarding next year. He remains under consideration but retaining him would be a safe bet and Williams needs to push on.

Another option would be looking towards young drivers, but taking that risk is not a route Williams really wants to go for.

It is unlikely to promote Alex Lynn, currently ninth in GP2 with one win, from his development driver role.

Lance Stroll, who moved across to Williams's young driver development programme for this season, will ideally move from Formula 3 into GP2 next year to continue his apprenticeship.

So Button is the best option available and he is exactly what Williams needs to regain the momentum and edge towards a position of being ready to demand that megastar driver in the future.

For Button, this is about more than the nostalgia of returning to the team that gave him his break in F1 at the start of the 21st century. Williams provides a place to secure that one last hurrah that has seemed so far away in the last few years at McLaren. It could be a very happy marriage.