One of the differences at the higher management level in pre-1948 days (and elsewhere in established commerce, such as with Banks), was the division between the Directors and the Management, something disappeared nowadays. The Directors, including the grand Chairman, were almost wholly part-time, similar to what would be known as a Non-Exec, and principally represented the interests of the shareholders/owners. The top position was the General Manager, but they were commonly not a Director, and only went to board meetings by invitation (and sometimes not even that). It would correspond to a Managing Director nowadays. The major railway Chairmen were often well known from other businesses as well.
The key managers, such as Chief Engineer (who did the civils) reported up to the GM. It was always an issue that the Chief Mechanical Engineer (who did rolling stock) was regarded as a cut above the other operational managers, and often had the same salary and status as the GM, which caused various ructions. Churchward (GWR CME) and Grierson (GWR Chief Civil Engineer) apparently had longstanding feuds and infighting.
When the LMS wanted to offer Stanier, from the GWR, the CME position, it had to go by a formal route. The GM of the LMS could not approach either Stanier or the GWR directly, he had to ask Lord Stamp, his Chairman, to approach Viscount Churchill, Chairman of the GWR, which they did over a pleasant lunch at Stamp's club. Churchill had to ask Sir Felix Pole, GWR GM, he in turn asked GWR CME Collett, Stanier's boss, who had to approve (or not) and ask Stanier to go over to Euston and have a word. Nowadays a headhunter would be appointed as an intermediary to approach Stanier directly.