I have a PCG-61611M laptop. On both UK and US Sony sites, this model is unknown. Their own detector app doesn't help.
What now? I need drivers!
Go to Start and Run. In the box, enter MSINFO32 and click OK. In the System Summary, see System Model. This is your actual model and often start VPC*, as opposed to the B/S they print on the bottom. I can only assume they still have lead pipes in Sony HQ.