The wooden structure at the far western end of platforms one and two faces an uncertain future.

Its function is being taken over by a new signal box on the opposite side of the coastline tracks just to the west of the station as part of a £25m improvement project.

The work by Network Rail involves a transformation of the signals around the station's three platforms and the branch line to Bognor Regis as well as extending the branch line further east.

The aim is to provide a modern signalling system and more flexible rail layout to limit delays and cancellations.

But the prospect of the current signal box being demolished has caused station users to campaign for its retention.

A petition with at least 750 signatures has been circulating among them.

Commuter Lesley Triggs has also applied for the signal box to be listed to recognise its historic significance to the village. The survival bid has been supported by the Arun Valley Rail Users' Association.

The signal box is believed to date from 1911 when the single Bognor branch line was turned into a double track.

Its cream and green colours have since been seen by millions of rail users.

Mrs Triggs has seen the signal box during 40 years of being a passenger at Barnham. She has commuted weekdays for about six years from her home in Eastergate to her job in a Bognor employment agency.

She said: "The signal box should not just be pulled down. It should be saved. Why can't it just be left there? It's an old fashioned design. In three years' time it will be a hundred years old and that will be worth celebrating.

"There can't be many signal boxes actually at the end of the platforms."

She has applied to the government's Department for Media, Culture and Sport to see if the signal box meets the criteria to become listed to ensure its survival.

Open days for rail enthusiasts to look around the disused box would help to raise funds for its preservation, she suggested.

Arun Valley Rail Users' Association treasurer Trevor Tupper, a regular passenger through Barnham, said: "I would be upset if the signal box went.

"It would be a pity to see it go. It's not in the way of the work that is being done. As far as I'm aware, it's the only London, Brighton and south coast signal box left of its type.

"It's a good example of Edwardian signal box design. It is a big signal box and it's relatively close to the ground. The others that are still around – at Pulborough and Billingshurst – are smaller and higher up. Littlehampton's signal box is away from the station.

"But Network Rail would need to be convinced there is a reasonable plan to keep it maintained.

"It would be good if somebody could put together proposals to get it preserved. I would certainly support them.