I guess a Ledy Boushh helmet with an "E" also exists. But letters are no unique traits for Ledy helmets as Kenner helmets can have letters as well. The reason is that Lili Ledy and Kenner used the same moulds (Hong Kong type) for their helmets. Better look at the colour of the plastic and the paint on top.
If you can confirm a Ledy helmet with an "E" inside, I will update this in the Ledy thread.
The Ledy Boushh helmet has the same mould as Kenner's Hong Kong helmet. The Ledy helmet is cast in a bit duller orange plastic compared to the Kenner helmets. In addition the grey paint on top is a bit more silver like. The Ledy helmets have little letters inside. ´F´, ´G´ or ´H´ have been confirmed for Ledy sofar.
REMARK: Also Kenner Hong Kong helmets have letters inside ('B', 'C', 'F', ...), so this is not a distinctive Ledy trait!!
Hope this helps.