In fact, Edgar Sheappard did play chess. The Chess Player's Chronicle
of 1854 gives a game in which he loses to Loewenthal, who gave him odds
of the exchange. That would make Sheppard quite a competent player,
though not master strength. Brien got similar odds from Loewenthal
around this time. I gather that the exchange was felt to be somewhere
between P+1 and P+2 odds.

Seconds in those days were not like seconds of today. There would have
been no help in analyzing adjournments; this would have been considered
very unethical. Seconds in other matches were generally chess players,
though not always first rate ones. I would not be surprised if Sheppard
was a financial backer of Staunton. He also could write scathing
letters, as he shows in the correspondence regarding the match printed
in the CPC.

I haven't read Harrwitz's side of the story; he had his own chess
magazine at the time. It would be interesting to have two people read
each side's version of the story without seeing the other side
presented, and see how they summarized the causes of the dispute over
the match.

Jerry Spinrad