The first Incorporated Television Company (ITC)/British drama series to be filmed entirely in colour. Stingray (1964) and Thunderbirds (1965) (both in colour) preceded The Baron but these were science fiction shows featuring marionette puppets.
Being filmed back to back with The Saint (1962) at Elstree's APBC Studios, the paths of Steve Forrest and Roger Moore often crossed. According to reports, Forrest found little time for Moore's trademark pranks.
In November 1965 production on the series was temporarily halted, after eight episodes, for series reformatting. Semi-regular cast members Colin Gordon (Templeton-Green) and Paul Ferris (David Marlowe, Mannering's assistant at his Mayfair shop) were permanently eased out by request of the US distributors ABC. Subsequently audience reaction was decidedly mixed, with some viewers complaining of the changes.
ITC had history in adapting John Creasey's characters for television, with Gideon C.I.D. (1964). They only brought over the two key names of The Baron and John Mannering, plus the fact that he dealt in antiques: Creasey's original (who featured in almost 50 books across 1937 to 1979 by the prolific author under the pseudonym Anthony Morton) was an aristocratic English Raffles/Robin Hood character, who owned Mayfair antique shop Quinns. As an ex-jewel thief he would assist police and the public when consulted.
Co-star Sue Lloyd recalled that Steve Forrest suffered from back pain, which at times was misinterpreted as part of a somewhat stiff performance.