This is the sort of coin that detectorists might find difficult to identify. It’s obviously a London penny of one of the Edwards but which one? The finder, Bill Byford, did very well to pin it down as a fourth coinage, pre treaty period, series G penny of Edward III, which is listed in the Standard Catalogue as number 1588.
On the obverse the legend reads +EDWARDVS REX ANGLI, with a cross 3 (4) at the start of the legend. It has annulets as punctuation marks and an unbarred letter N in ANGLI. On the reverse the legend reads CIVI TAS LON DON and both of the Ns are unbarred.
There are several varieties of series G, mostly based on the positioning of annulets, saltires and pellet stops in different places on pennies. Some coins have lots of different marks but Bill’s find has only annulet stops in the obverse legend; as such it belongs to class Gb.
The catalogue price for Edward III series Gb in Fine condition is £20, which is the same as Edward I class Xc-f pennies. However, I’d estimate that a detectorist might find around 50 of the latter for each one of the former.
This Edward III London penny is better looking and a better strike than usual and overall it would grade about VF. Pricewise, I’d say that an Edward III specialist should be more than willing to offer £75 for this coin.