Re: Alternative approaches...
Yes, probably an issue in size, would guess 0.6m^2 or more.
Not sure about the device automatically implies heraldic emblem part though. If they meant that you'd think it would be more specific; to heralds a device is a part of a coat of arms, not the whole thing. And a personal striped flag, for example, might not be recognised as arms, there are some instances in the past couple of decades about the crests football clubs use not being registered, one factor in which is that not all of them are necessarily arms. Being on a shield is apparently a clue, which the skull and cross bones is not. Those not of British descent might have other personal devices that are not English arms.
However the whole field of Heraldic Law and Court of Chivalry doesn't appear to have any primary legislation, making it a seriously difficult field for the enthusiastic amateur to get a handle on, and the court largely acts to prevent people using the registered arms of others. I will bet that council planning departments do not want to end up in cases at the Court of Chivalry to try to decide whether someone is entitled to bear particular arms!
Alternatively: flag with a massive picture of his iPhone. In a skull and crossbones cover.
Biting the hand that feeds IT
