Mr Hopson, 35, who suffers from Aspergers, a form of autism, went missing from his home address in Southwater Road, St Leonards, exactly two weeks ago on Monday January 25, at around 2.30pm.

He said he was going for a walk but did not return home.

Police are following up possible sightings of him in Tunbridge Wells, Hastings, Eastbourne and Hailsham. He is known to like walking and uses the local bus network.

His mum Dawn, who lives in Crowborough, said: "It's dreadful and we don't know what to do. Police are looking for him everywhere.

"He disappeared before at the beginning of December while out walking from Battle to Heathfield. He did not have his mobile phone with him and had to spend the night in a bus shelter."

Mrs Hopson said her son had mistakingly missed the last bus and was found the following day waiting for the next one at the shelter.

She said: "Piers enjoys walking everywhere. In recent weeks he has walked around Rye and Winchelsea with staff from his care home."

His mum said her son had £45 on him last Monday and was wearing a mushroom-coloured anorak, dark trousers and brown shoes.

There was a TV appeal last Wednesday (February 3) which resulted in people calling in to report possible sightings, one of them being in Hastings.

Police are examining CCTV footage from both Ore and St Leonards Warrior Square stations, as well as Tunbridge Wells station.

Officers also visited the last known whereabouts of Mr Hopson exactly a week after his disappearance.

They handed out posters and spoke to passengers and staff.
Leaflets with Mr Hopson's photograph have also been distributed across the South East and London.

If anyone finds Mr Hopson and he is unwell, please call 999 immediately to request police and ambulance attendance. If he is safe and well, please contact Sussex Police on 0845 60 70 999.