These pens went into production in 1948 and were popular with King George VI.  They don’t appear very often and when they do they are usually pricey.  This one is generally very good but there is brassing on the wide cap band.  The gold nib is unusually large for a Wyvern and it bears the Leicester Dragon imprint.  The pen is identified by an imprint on the blind cap.

I’m assuming it’s crocodile but it might be alligator.  I’m not well up on my crocodilia.