Posts: 272 Location: Scotland
Wed 02 Dec, 2009 5:16 am
your best course of action is to contact the portable antiquities scheme:
http://www.finds.org.uk/index.php
its almost certainly not going to be classed as treasure find, given it's a relatively modern (ie, well past 1700) blade, and not containing any precious metals, but they are much more likely to be able to point you in the direction of people who can assist, ie, the museum of london, perhaps.
what they can do is also aid in conservation - its a river-find, and that mud has effectively sealed in the iron for the last few centuries, and protected it. having been cleaned away, its now in danger of oxidisation eating much deeper and more rapidly into the metal, meaning it could decay into a far worse condition over time. it really needs to be conserved, and sealed to prevent that from happening, and they should be able to aid you in that process.