Robin Stormonth Darling was a stockbroker who, as senior partner of Laing & Cruickshank at the time of the Big Bang reformation of City working practices in 1986, presided over its development into one of the bigger London firms. He also applied his knowledge of the financial markets to several regulatory roles.

In the early years that Stormonth Darling worked for Laing & Cruickshank the firm was an old-style stockbroker that dealt predominantly with private clients — that is, individual investors. As he rose to its head, however, the firm’s activities broadened. It began to work more for institutional customers, such as large pension funds, and dedicated more time and energy to analysing the performance and prospects of listed companies.

In 1982 Laing & Cruickshank was merged with its rival McAnally Montgomery, and Stormonth Darling was named head of the enlarged business. He said that the deal would enable staff at both firms to adapt to patterns of stockbroking that — he correctly predicted — would change substantially over the following decade. “Increasing advantage,” he said, would come to “strong firms with a well-spread business”.

As the stock market boom of the 1980s took hold and 1986 brought fundamental change to the operation of the London Stock Exchange, “Laing and Bang” — as the firm was sometimes known — became one of the better-known securities’ dealers.

Stormonth Darling was a senior figure in the Square Mile when hopes for self-regulation of the London financial market were at their peak in the early 1980s. Though the system was superseded by statutory powers and the creation in 1997 of the Financial Services Authority, the recent crises have led some to believe that selfregulation of the sort championed by Stormonth Darling might have proved a more effective brake on excess.

As a practitioner who also served as a regulator, Stormonth Darling spoke favourably about the birth and growth of the Unlisted Securities Market. The now-defunct USM operated alongside the main Stock Exchange list of quoted shares. It had less stringent eligibility criteria and was established as a nursery for smaller and younger firms wanting access to capital.

In 1984, acknowledging the more adventurous nature of investments in USM companies, Stormonth Darling said: “Eighteen months ago, it was a healthy and boisterous child. Now it’s beginning to mature into a child with a bit of sense as well as being boisterous.” But attempts to calm the overexcited, almost casino-like investment atmosphere of the USM were only partially successful. Many shares in USM companies were badly hit by the stock market crashes of October 1987 and October 1989 and the USM’s reputation became tarnished.

Robin Andrew Stormonth Darling was born in Buckinghamshire in 1926. He was knocked down by a bus in Gerrards Cross at the age of 8, suffering injuries to his pelvis and ribs, which left him with a slight limp. The handicap did not prevent him from winning the steeplechase at both junior and senior levels at Winchester College, or from captaining the school’s second cricket XI. He was senior commoner prefect (joint head boy), showing a particular talent for maths and Latin.

He joined the Fleet Air Arm in late 1944 and became a pilot, but the war ended before he saw any action. In 1945 he joined the Army as a regular soldier, a move that gave him the unusual experience of having served on land, sea and air. He was commissioned into the 9th Lancers, and, after serving in Palestine, was appointed ADC to the General Officer Commanding-in-Chief in Scotland, Lieutenant-General Sir Gordon MacMillan, stationed at Edinburgh Castle. For the last two years of his service in the Army he was an instructor at Mons Officer Cadet Training Unit at Aldershot, where he earned a reputation as a strict and demanding disciplinarian. He also formed many lasting friendships.

In 1954 he joined Laing & Cruickshank, one of the City’s oldest established private-client stockbrokers, founded in 1882. In those days many stockbrokers wore a short black coat, black waistcoat, striped trousers and a top hat. It was an outfit that gave Stormonth Darling, who was tall, an imposing presence. He soon became a partner, and was chairman from 1980 until the sale of the firm to Crédit Lyonnais, the French bank, in 1987.

Attracted to the City’s regulatory aspect, Stormonth Darling was from 1981 until 1985 chairman of the influential Quotations Committee of the Stock Exchange, a body that among other things, examined suspicious or controversial share trades, and from 1985 to 1990 he was on its Disciplinary Appeals Committee. He was also deputy chairman of the Takeover Panel, which ensured fair play in the sometimes heated business of mergers and acquisitions, and served with the Securities and Investment Board, the predecessor of today’s Financial Services Authority. As an experienced poacher turned gamekeeper, he could have made a more significant contribution as a regulator, but his credentials were undermined when, under his watch as chairman of Laing & Cruickshank, one of the firm’s representatives was found to be involved in the Guinness scandal in which a number of people conspired to support the price of Guinness shares in the takeover battle for Distillers in 1986.

Outside the City of London, Stormonth Darling was appointed a member of the board of British Motor Corporation, in 1960, where he remained for 16 years. It was later to become British Leyland and included Austin, which developed the Mini, Jaguar, Morris, Rover and Triumph among its subsidiaries.

After retirement from his full-time activities in the City, Stormonth Darling served on the boards of several investment and other financial companies, notably the Ptarmigan International Capital Trust. He was also Honorary Consul for Mexico in Scotland for 15 years, proudly flying the Mexican flag alongside the Saltire at Balvarran, his Perthshire home that he had inherited from his father in 1961.

Stormonth Darling was a first-class shot who cut an impressive figure striding the moors in his kilt. He was an enthusiastic skier and pilot, and organised a family fathers and sons cricket match at Scone Palace, near Perth, in the 1970s and 1980s.

He regularly completed the Times crossword, and was a quick performer in any mental arithmetic or word game. Accused by Carola, his wife, of being irritatingly good at answering the questions while watching the television programme Countdown, she put his name forward for the show and he took part in it in 1992, billed as “a Scottish laird”. He won two rounds. Richard Whiteley, the host of the programme, wrote later that he was “the tallest and most gentlemanly contestant we ever had”.

Stormonth Darling married first Susan Clifford-Turner, secondly, Harriet Heathcoat-Amory and thirdly, Carola Brooke. He is survived by Carola, his wife of 28 years, and by a daughter and three sons of his first marriage and by two stepsons.

Robin Stormonth Darling, stockbroker, was born on October 1, 1926. He died on October 17, 2009, aged 83