They are the faded snapshots of a policing era from long ago. Images of smartly turned-out “thief-takers” from the time of Dixon of Dock Green.

But in a mystery almost worthy of Sherlock Holmes himself, images and artefacts documenting the history of the Black Country’s finest have been missing for 40 years.

Only a handful of photographs, pieces of equipment and records from the service in the Black Country are housed at the West Midlands Police Museum in Birmingham.

Now curators are trying to piece together a clearer picture of the region’s policing history by appealing to former officers and their relatives to come forward with new items.

Retired bobby Dave Cross, who has been keeper of the Birmingham museum for 12 years, said the lack of Black Country exhibits was “embarrassing.”

There are only around 20 exhibits from the Black Country, compared with some 6,000 from the Birmingham area.

He has been told that many items were loaded onto a van in Brierley Hill in around 1966 when the West Midlands Constabulary was formed.

Mr Cross said: “I don’t know where they went, I don’t know who authorised it and I don’t know what’s happened to it all.

“The museum is embarrassingly lacking in its Black Country material. If people can find anything at all, from the 1850s onwards, I’d like them to contact the museum.

“It’s our history. It’s important that we are able to know what was happening in our past.”

But it’s not all bad news. The museum has a “charge book” from Walsall dated 1914-16. It contains a full list of prisoners from the era, and is currently being digitised ready for for it to be uploaded on to the internet in the coming months.

* Anyone who can help build the museum’s Black Country collection should call Mr Cross on 0845 113 5000.