McLaren & Williams' focus on remaining independent teams is causing their current lack of competitiveness, says Sky Sports commentator Martin Brundle.

Both outfits have steadily fallen down the pecking order in recent years and by the end of 2018 were indeed finding themselves filling the back two rows on the grid as a result of problems with development.

According to the former McLaren driver, however, their problem is much more than just errors in design, instead, it is the fundamental shift Formula 1 has taken.

"The problem with Williams and to an extent McLaren is they are outside where you need to be these days in F1," Brundle said at the Autosport International Show in Birmingham.

"You either need to be a manufacturer team or a Haas and Toro Rosso-style B-team with the hand-me-downs.

"That leaves a void in the middle where Williams and McLaren find themselves because they're not works teams and they're certainly not B-teams."

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McLaren remains a big enough entity that they are less inclined to seek manufacturer help, though did strike a partnership with Honda and is working closely now with Renault also.

Williams has also been reluctant to increase ties with Mercedes and both teams maintain that position under the belief it is impossible to win in F1 as a customer outfit.

"Let's wait and see if that works for them. I hope it does, in a way," Brundle continued.

"But it's tough for them when they're fighting a team like Haas, that has a completely different business model, and they're getting a lot of stuff from Ferrari and Dallara."

While such collaborations with manufacturers are being looked into by F1 bosses when deciding future regulations, the respected pundit admits ending the practice would cause more harm than good.

"We've only got 20 cars on the grid. You've got to look after your maverick billionaires, you've got to look after your manufacturers as well," Brundle noted.

"There's got to be something for everybody.

"I'd imagine [F1 motorsport director] Ross Brawn is fighting over this every morning and every other morning and afternoon trying to somehow find a template for the future of Formula 1."