Do they cut the corner of my old passport immediately when I apply for a UK passport renewal at VFS Bangkok?

When applying for a UK passport renewal at VFS Bangkok, the corner of your old passport is cut off after you receive the new one. You will need to provide copies of every page of your old passport when submitting your application, and you can still use your old passport with visas until it's clipped. Once your new passport is ready, you return to VFS to hand over your old passport, which will then be clipped.