Somehow we tend not to think of Birmingham as a city of art collectors, so an exhibition opening at the Barber Institute later this month is likely to prove a revelation.

Behind Closed Doors is the first attempt to reflect the range of art owned by private collectors in the city.

Comprising almost 40 works, it is the result of pioneering research carried out over the last two years by the Barber's senior curator, Paul Spencer-Longhurst, and guest curators Michael Cullen and Tessa Sidey.

You might imagine that private collectors, for fairly obvious reasons, would want to keep their prized possessions as private as possible.

But appeals in the regional media brought floods of visitors to drop-in sessions at the Barber and Birmingham Museum & Art Gallery to have their works assessed for possible inclusion.

Other works came to light through word-of-mouth on informal gallery networks, resulting in the curatorial team visiting more than 100 private collections in the Birmingham postal area.

They came up with some remarkable discoveries, ranging in date from the 15th century to the beginning of the 21st.

They include portraits by Van Dyck and Rossetti, a Durer woodcut dating from about 1505, watercolours by Turner and Delacroix and an Impressionist painting by Boudin, as well as more predictable Birmingham artists like David Cox, Walter Langley and William Gear.

The 20th century is well represented, with works by Picasso and Barbara Hepworth, as well as living artists like David Hockney, Paula Rego and Cornelia Parker.

Dr Spencer-Longhurst says: "This exhibition seeks to redefine the nature and status of collecting in Birmingham today. The private collections we have visited, and from which we have been privileged to chose works, demonstrate that the practice is thriving in the city and has an exciting and diverse range."

Behind Closed Doors opens on January 25 and runs until April 27. There will be a fully illustrated catalogue and a programme of talks and related events for adults and children.

On March 27, the Barber's director, Ann Sumner, will give a talk about collecting in Birmingham at Christie's London headquarters.