The photos work!

The first is a BSA made between 1936 and 1939. The serial number should start with A or C rather than 0. Could it be a C? Overall length will tell us which model it is if you can confirm this and if the prefix is unclear. If the etching including model details and patent numbers on top of the cylinder is readable, this will increase the value.

If the etching has not survived, I'd still conservatively estimate value at £250+.

The second is a Langenhan made airgun that was imported by Lincoln Jeffries just before he invented his underlever, so probably dates from around 1903. Is the top of the cylinder stamped H The Lincoln?

I've seen these priced at around the £120-£150 mark at fairs, depending on the clarity of markings, degree of barrel wobble and overall cleanliness.

Hope that helps.

John