Broad's superb innings beat the 122 made by number nine Gubby Allen against New Zealand in 1931.
His best score in his previous 31 Tests was 76 against South Africa at Lord's in 2008 while his career-best innings was 91.
When he made his Test debut in 2005 there were high expectations that the Nottinghamshire seamer could become their next all-rounder.
However, that failed to materialise and, with an average of 24.39 going into this Test, the 24-year-old found himself batting at number nine.
On Saturday, Broad and Trott will seek to surpass the England record eighth-wicket partnership of 246 against all countries, which Allen set with Les Ames (137) during that same match 79 years ago.
And later in the match he will hope to take the six wickets he needs to bring up his century of Test wickets.
The hosts, 2-1 up in the series, were reduced to 47-5 by a brilliant spell of swing bowling from 18-year-old Mohammad Amir after resuming on 39-1.
But Trott and Broad showed the grit and technique that the top-order had not to move England out of trouble and into a strong position.
"We said when I joined Trotty out there it was just important to have a clear plan of making five at a time, get to 105, 110 and just build from there. That took the emphasis off what the pitch was doing.
"He was unfazed, like he has been throughout his Test career. We knew we didn't want to give away a cheap wicket at the end and we're happy to face the seamers tomorrow with a 30-over-old ball.
"The overhead [conditions] play a big part here, but we've seen the wicket get flatter and flatter as Test matches go on so it's important to put a big score on the board first.
"At 100-7 it wasn't looking too likely but it's important Trotty and I build on that and get to around 400."
Broad's name will now go on the prestigious honours board at Lord's - something his father Chris, an opening batsman, failed to do during his career.
And his century also boosted his chances of moving above Graeme Swann in the batting order.
"I'm dying to bat eight, Swanny is dying to bat eight - we'll keep battling and hopefully both score runs," added Broad.
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