Hi Simon, are you sure you have a Thunderbolt display? Does the connector have a lightning bolt symbol? There was also the Cinema Display with a screen symbol. Same plug. Fits into the Thunderbolt socket, but is a Mini DisplayPort plug. It does not work with the adapter. Although it fits. I have a Thunderbolt display and the adapter. However, I haven't used them together yet. I will catch up. I'm interested to see if it works (MacBook Pro, Apple Silicon). Best regards

Yes, the connector has a lightning bolt as a symbol. And when I go to the info about the old Macbook pro, it says that a Thunderbolt Display is connected. There is also a separate Thunderbolt port on the display. Now I have used the Thunderbolt port, which goes in a cable together with the Macsafe connector from the display. I could also try to connect a Thunderbolt2 to Thunderbolt 2 adapter with the Thunderbolt 2 to Usb C adapter and go to the MacBool Air that way. xD Could that help?