Becoming more and more common unfortunately.
"Secure" car park probably has cameras and the thieving toe-rags are more than likely known to the local boys and girls in blue. Hopefully you'll get it all back.
I know it doesn't seem real that a 5 string bass with "Musicman" on the headstock is selling for £200 but that, unbelievably, is what that sell for.
GLWTS
Currently £36 - it won't sell for this but one can only hope that it doesn't attract too much attention (he says posting it here).
https://www.ebay.co.uk/itm/256106368050?hash=item3ba1210c32:g:0z8AAOSwtOFkhZR8&amdata=enc%3AAQAIAAAA4M%2FxKL74C7LOXD1LbSpEwXXG90YXnpfriX0cqBJ9xs5%2BaMpES%2FUGWDhnv2Zh2e8lM5CGBhnIGS3f2MnHGb%2B7l%2FLQADuFESIzfCWyqNjnDPjW6jaEjcFew6O%2FraUYekjKg9CJgXpH3jYXKUjsa8E0zgY5LkraOajCmsCfGprH7O1XUZNGOTsK6zDfIvezkBYwboXd563Z4Mz87db0BN%2F2t1qIESkGmObylrSn8cIVJaKtgC%2FQUiP%2FAKrIbGqvu9495%2FmJ8mh%2FXBbeMKJPbB3QJuoBl7rBSJp3a2s9Gn5rfUXD|tkp%3ABk9SR6iwmYuYYg
Took the bass up to my electronics tech, Mal Crawford in Stevenage to have a look at the electronics. I'm pretty sure it's something really simple stopping the bass making any noise. Mal will spot it in no time but will taunt me about it forever...
There is the fall back position of "it's not mine - it belongs to xxxx and I'm borrowing it/ looking after it for him so his wife doesn't know he bought it."
This works unless your wife knows his wife.