Lenovo Thinkpad Dock compatibility

I have a Dell XPS 13 Plus 9320 and was hoping I could use my old Lenovo Thunderbolt dock with it (type 40AC).  I've updated the laptop in all respects (bios, drivers) and installed the lenovo drivers for it.  In spite of this, all the dock does is provide power, the laptop doesn't seem to recognise it as a dock (i.e. it doesn't appear in device manager) and there is no connection through the graphics or USB ports on it.

I appreciate Dell may want to restrict my ability to use 3rd party docks to ensure that I only use their own (not unreasonably) but I wondered if I was missing anything that might allow me to use this dock?  Even if just as a USB if not for display would be something.

Thanks for any advice,

Will