Mitchell Johson

Chris McCormack/The Sunshine Coast Daily

MATTHEW Hayden believes Mitchell Johnson should be forgiven for his Ashes bowling woes as his inconsistency is also a major strength.

Hayden leapt to Johnson's defence after he leaked 77 runs from his first 11 wayward overs to help England onto the front foot on day one of the second Test at Lord's.

The former opening batsman rubbished claims Australia's pre-series spearhead may be under pressure to retain his place with Stuart Clark and Brett Lee waiting in the wings.

Despite Johnson conceding 15 boundaries from an embarrassing number of loose deliveries with the new ball, Hayden said the left-armer was still clearly Australia's No.1 quick.

He cited the 27-year-old's early series haul of seven wickets at 34 as still being more than the entire English attack's return from less overs.

Hayden felt Johnson's inaccurate spells in the first and second Tests was the unpredictable nature of his action as a left-arm fast bowler, who are traditionally more wayward than right-armers.

He insisted the inconsistency of his former teammate, who bounced back with the scalps of Alastair Cook and Matt Prior to finish the opening day with 2-107, also helped to make him a more dangerous wicket-taker.

"For example do you think (Prior) who Mitchell bowled with that unbelievable inswinger was thinking that was the ball that was coming? No chance," Hayden told AAP on Friday.

"In the first Test do you think (Ravi) Bopara was sitting there thinking this is going to be a slower ball and getting deceived and spooning it up to point.

"I'm not going to get on his back for his inconsistencies because in short, I think that's his strength."

With Clark, the player of the last Ashes series, waiting on the sidelines and Lee due back from injury in the upcoming Tests, Australia will think seriously about changing their attack if they fail to win at their happy hunting ground at Lord's.

But Johnson should be a protected species according to Hayden.

"He's still No.1 pick in my book, Mitch," he said. "He's the No.1 seed, not just for (his bowling) but also because of the fact he's just a weapon of destruction in the other two elements of the game - for his fielding prowess and batting skills.

"That's another great strength. We were not winning the South African series without Mitchell Johnson.

"So just a Test and a half later and he's performed a fractionally under par he's no good? No, he's a great talent.

"He's still taken more than twice as many wickets as any of the English bowlers so far in the Ashes."