Jenson Button says Honda have made massive improvements to the deployment of electrical energy over the winter after completing his first miles in the 2016 McLaren.

The 2009 world champion highlighted deployment as the key reason for McLaren's struggles last season and was delighted to find the situation had improved on the first day of pre-season running.

In all, Button completed 84 laps - in excess of a full race distance at the Circuit de Catalunya. This time last year, the newly-forged McLaren-Honda partnership registered a mere six laps.

After a difficult campaign, Button was understandably beaming in his post-session press conference and his smile could get wider with Honda set to deliver further improvements before Australia. It is understood that the engine manufacturers will deliver an updated version of the power unit for next week's test in Barcelona.

"It is difficult to say in terms of power because this won't be the engine we take to the first race. The deployment is so much better. I don't know if it is the same as the other guys have but it feels like it is. That is a big step for us," Button said.

Speaking with Sky Sports News HQ's Rachel Brookes, McLaren driver Jenson Button revealed he was glad to be back in the driving seat after the winter break Speaking with Sky Sports News HQ's Rachel Brookes, McLaren driver Jenson Button revealed he was glad to be back in the driving seat after the winter break

"This isn't a track where you struggle for deployment over one timed lap, but over a long run we were struggling massively and losing four or five tenths on a lap, whereas now we don't so we have gained lap time back over a long run.

"It is much better, very easy to understand the deployment and to play with it and it listens to change which is good. It is good to see all the hard work over the winter has paid off."

Button toyed with retirement during 2015, but admits he would have been frustrated sitting at home had he hung up his gloves.

"I was happy 10 minutes ago driving an F1 car," he added.

"It's what I've missed for three months, it feels like the longest break I've ever had in my career. I'm so glad I didn't retire last year because I have missed it massively."

Hamilton hails 'best first day ever'

The latest from Formula One's pre-season testing in Barcelona. See the new Mercedes, Mclaren and Ferrari in action. The latest from Formula One's pre-season testing in Barcelona. See the new Mercedes, Mclaren and Ferrari in action.

The Sky Sports F1 Digital team will be providing live commentary from dawn until dusk on all four days of both Barcelona tests while Sky Sports News HQ will also deliver live updates from trackside.