This is the wartime flare gun used in up to 16 armed robberies on shops and garages in Worthing.

In a major breakthrough, police recovered the unusual weapon along with items of clothing used to disguise the raider's identity.

It was found by sniffer dogs near St Andrew's churchyard, Tarring, after the last robbery at Tarring Village Stores, Church Road, on March 21.

Police now believe the same weapon may have been used in up to 16 of the 21 armed robberies in Worthing since Christmas.

The gun, along with some clothing, will be shown on BBC's Crimewatch programme tonight.

The gun is a double-barrelled flare launcher dating back to the Second World War. It was made in 1942 in Germany, possibly for the navy, by German company fsz (krieghoff).

Detective Inspector Jeff Riley said the weapon could have caused nasty injuries if fired at point blank range.

He said: "I think this development is very significant, and the fact that it's a German pistol is also significant. There can't be that many of its kind in the area."

Sniffer dogs also retrieved a black Firenze scarf and a black baseball cap with a red bat-style logo, which the robber was seen wearing in the 15th raid, at Ladbrokes in Rowlands Road on March 14.

Police also released video footage yesterday of the first raid, at the Murco garage in Sompting Road on December 28.

In the video, the raider is shown wearing a hooded top and a scarf to hide his face. He can be heard asking the shopkeeper to open the till in a calm, polite manner.

Mr Riley said: "He does sound very calm and not flustered at all. He is very well-spoken. There is no active violence used towards people. He brandishes the weapon, but he never shoves it in people's faces."

Mr Riley said the gun was the most important piece of evidence found so far.

He said: "There are a number of possibilities as to where this weapon has come from. It might not be stolen - it may belong to someone who doesn't even realise it is missing."

Crimewatch is at 9.05pm tonight. Anyone with any information should contact the Operation Texan team on 0845 6070999. There is a £10,000 reward for information leading to the raider's arrest.