An historic bust and its bronze plaque were stolen from a park days before a VIP visit.
The valuable items, dating from 1875, were taken from a memorial at West Smethwick Park which honours the Chance family, who were internationally-known glass manufacturers in the area.
The theft was discovered just days before Toby Chance travelled from South Africa to see the park, which his great-grandfather James gave to the people of Smethwick.
Mr Chance visited the park yesterday accompanied by a South African film crew. The crew is making a documentary on the Chance Glass Company, which produced glass for lighthouses across the world.
Sandwell Council's cabinet member for culture and leisure, Coun Linda Horton, said: "The visit has been organised for a long time and the plaque is believed to have been taken in the last few days.
"The timing of this is absolutely unbelievable and extremely unfortunate.
"We have made exhaustive inquiries to try and replace the plaque, but have been told a bronze of this significance cannot be replaced overnight and may take months to remake."
Coun Horton also appealed to those responsible to "find it in their hearts" to return the plaque which, she said, had huge sentimental and historical value.
"We are particularly keen to alert scrap metal traders and to urge them to contact the police or our rangers if they are offered the plaque."
The visit has been largely organised by the Friends of West Smethwick Park. Chairman Graham Price said "I am appalled at the mean-spiritedness of the people who have taken such an historical artefact away."
* Anyone with information is urged to contact the park's urban rangers on 0121 552 4214 or police on 0845 113 5000.