Some older pictures are licensed under the Creative Commons Non-Commercial Attribution Share-Alike license. More recent ones are not. The reasons for this are explained here. Check the individual image to be sure. Regardless, if you would like to use a picture for non-commercial purposes, please get in touch and I'm likely to license it for free.

Some of my pictures are available for commercial use through Alamy. You can find them here. If you'd like to commercially license something that isn't available through Alamy, or you have other queries, please get in touch by email.