Mr Sonning is the head of Sonning's, boat-builders at Potter Heigham who have boats cast off and shackles stolen in The Big Six (BS10,32).
Frank Farland's firm Farland, Farland & Farland is solicitors to Sonning's (BS13,16), so has to advise whether to prosecute George Owdon and Ralph Strakey; probably not if they write a full confession (BS22). Previously Frank had been in an awkward position about the supposed involvement of The Coot Club members (BS13).
At the end of The Big Six, a couple of Sonning's workmen give friendly waves to the Death and Glories.