An irreplaceable cigarette case stolen in a burglary at a museum in Southampton has been returned, anonymously.
The case, that belonged to Spitfire designer RJ Mitchell, was stolen from the Solent Sky Museum last month.
The museum's trustees said it was returned in good condition, inside a padded postal bag.
The case has been put on temporary display, with other items which once belonged to Mr Mitchell.
Trustee Andy Jones said: "We were thrilled, shocked and somewhat confused, all at the same time when we opened the package to reveal the cigarette case had been returned to us.
"It really is such a relief to have this historical item back in safe hands.
"We are so pleased to have the case back and we want to share this artefact with visitors to our museum, as it was very nearly never seen again and what a great shame that would have been."
The case was given to the museum by Spitfire test pilot Jeffrey Quill, who was one of Mr Mitchell's close friends and colleagues.
It was among a number of items taken during the break-in on Monday 9 March.
The museum, in Albert Road, showcases the history of aviation in Southampton and the Solent.