A motorbike and sidecar hit a “dip” in the road before veering into a concrete bollard at 100mph killing the sidecar passenger and seriously injuring the driver, an inquest heard.

Mother-of-three Charlotte Tagg never regained consciousness after being “thrown off” on the Madeira Drive track.

Eyewitnesses yesterday gave their account of the fatal incident at the Brighton Speed Trials on September 8, 2012.

The inquest heard driver Roger Hollingshead and his passenger had already safely completed two runs of the quarter mile track without incident.

But on their final run, shortly before 6pm, they hit a “dip” in the road before veering off to the right.

Safety crew member, Michael De Young, said the vehicle went into the “slight depression” in the road while travelling in excess of 90mph.

He described the front wheel “lifting” and then veering to the right when it came back down.

He said: “It came into contact with something at the side of the track which I later found out was a bollard.

“It then appeared to spiral horizontally, bouncing off the curb and fence two to three times, then barrel rolled.”

The driver and passenger were thrown from the bike.

Spectator Richard Stannard, who was standing near the finish line, said he saw someone “flying down the road” after being catapulted off the bike.

One of the race marshals, Alan Smith, said some vehicles “bottomed out” while others “get a wiggle” after hitting the dip in the track.

He described seeing Miss Tagg and Mr Hollingshead “get a wiggle” from the dip shortly before veering off the road.

Another marshal, John Elleker, said the dip had always been there but may have got bigger over the years due to the high amount of traffic and other events.

He added: “I really don’t know if it caused the problem or not.”

He told the Brighton Magistrates’ Court hearing the engine was still “screaming” as it crossed the finish line before “all hell broke loose”.

A paramedic was on the scene in seconds and focused on the injured driver – after judging there was little he could do to save Miss Tagg.

Giving evidence Mr De Young told how he held Miss Tagg’s head as she lay motionless on the track and continued to speak to her and reassure her until she was taken to the Royal Sussex County Hospital.

She was pronounced dead just after 8pm on the same night.

The inquest previously heard how Miss Tagg, of Beck Row, Suffolk, only signed up for the historic speed trials after another rider had pulled |out.

The inquest continues.