I have a writing buruea that belonged to my late mother,I think it is antique, how do I identify if it is and how could I put a value on it, it is about 70-80 years old, built with solid timber frame and sides with the draw fronts and drop down lid of 20mm veneered ply. The drop down drawer has a brass bar that pushes out two wooden supports for the lid as it is opened. I would appreciate any help.