Joe Rukin from Stop HS2 told ITV News Central that he remains optimistic about the outcome of today's review.
The High Court is expected to give its ruling on a number of legal challenges to the government's plans for HS2 later today.
Opponents of the high speed rail plans are asking a judge in London to declare the multi-billion pound project legally flawed and to reconsider the plans.
The first phase of HS2 would see a high-speed railway line running from London to Birmingham.
If successful, the legal challenge could potentially delay the scheme for years.
– Fazle Elahi, shopkeeper
The ambulance came really quickly. It looked like the William Hill sign had hit him. A woman at the scene was crying. He wasn't moving.
Health and safety investigators entered a flat above the shop to take photographs of the sign, which was made of metal and measured approximately 30ft.
A bunch of flowers had been left at the scene by a member of the public.
Ken Osbourne, who works at the nearby Woody Grill restaurant "Hundreds of people walk past here every day. It could've been me or any one of them. The shop has been there for about 10 years."
Ioana Nita, was working at a nearby restaurant and said; "I don't know how that can happen. The sign is huge. Everyone said he was just walking past the shop.
"I cross that way five times a day. That could have been me."
The sign, which had covered the length of the shop front, fell on to the pavement on a main road in Camden, north London.
Police erected a forensic tent on the pavement to cover the place where the man was killed, and cordoned off the surrounding area.
Ioana Nita, 21, was working at a nearby restaurant when the accident happened.
"I'm shocked. We heard a very loud noise. Me and a colleague went outside and saw the guy lying on the floor," she said.
"Five guys picked up the sign and it was put on the side. His hands were covered in blood and he wasn't moving.
"Lots of people were in a circle around him, then the ambulance arrived and they were trying to get him back to life, pressing on his heart."
Ken Osbourne, 28, who works at the nearby Woody Grill restaurant, said: "I saw the guy lying down in the road, covered in blood.
"The main impact was clearly on his head. I saw them trying to resuscitate him in the back of the ambulance."