England at the close were 326 for six in their second innings, a lead of 261 runs, with Broad 47 not out, having so far helped Bell add an unbroken 108 for the seventh wicket.

Broad, however, had a massive slice of luck when given not out on 37 by experienced Pakistani umpire Aleem Dar after Australia appealed for a catch by captain Michael Clarke at first slip off teenage debutant spinner Ashton Agar.

Broad stood his ground and, with Australia having used up their two permitted reviews in the innings, the tourists ultimately had to accept the verdict even though television replays showed a thick edge that had first come off the gloves of wicketkeeper Brad Haddin.

Australia coach Darren Lehmann's reaction was plain to see and on the field tempers frayed when fast bowler James Pattinson continued appealing after Sri Lankan umpire Kumar Dharmasena had rejected an lbw appeal against Bell, on 94.

Dharmasena spoke to Pattinson, presumably telling him to calm down, and replays showed Bell had indeed got a big inside edge.

That Ashes-holders England were well-placed could be seen from the fact that no side has scored more in the fourth innings to win a Trent Bridge Test than England's 284 for six against New Zealand in 2004.

This innings, which saw him pass 6,000 runs in his 89th Test, was an especially important one for Bell.

A criticism of the 31-year-old Warwickshire right-hander is that he has all too rarely scored runs when England most needed them.

And after 35 innings without adding to his tally of 17 Test hundreds, England dearly wanted the stylish Bell to go on to three figures with this knock.

By the close Bell, in at 121 for four, had almost done just that, having batted for nearly five-and-a-half hours while hitting 12 fours.

England resumed Friday on 80 for two, with captain Alastair Cook 37 not out and Kevin Pietersen 35 not out.

But they lost both senior batsmen before lunch.

Pietersen looked in good touch while making 64 out of a third-wicket stand of 110, striking 12 fours, but fell when he played on to Pattinson, the most threatening of Australia's seamers.

Left-handed opener Cook spent more than four painstaking hours compiling exactly 50 runs.

But he became Agar's first Test wicket when he aimed leg side across the line of a delivery from the 19-year-old left-arm spinner -- who on Thursday made 98, the highest score by a Test match No 11 -- had him caught by a leaping Clarke at slip.

Jonny Bairstow didn't settle and fell for 15 when he pushed forward to a well flighted Agar delivery and was caught behind by wicketkeeper Brad Haddin.

Bell, on 34, was given out by Dharmasena after an lbw appeal by medium-pacer Shane Watson.

However, Bell reviewed the verdict and, with replays showing the ball missing leg stump, he was reprieved by South African replay official Marais Erasmus, who'd angered England with some of his decision-making on Thursday. Matt Prior scored briskly while making 31.

But, after Australia had taken the new ball, the wicketkeeper gave his wicket away when he hooked a Peter Siddle bouncer straight to Ed Cowan at midwicket.

England's seventh-wicket duo remained watchful after tea but Broad, on his Nottinghamshire home ground, gave the crowd something to cheer when he cover drove left-arm quick Mitchell Starc and square cut Pattinson for two stylish fours.

He gave a half chance when, on 29, he swept at Agar and short leg Cowan, on the move in anticipation of Broad's shot, failed to hold a right-handed chance. (AFP)