FORMER Monmouthshire High Sheriff and Deputy Lieutenant Robin Herbert CBE has died at home at the age go 89.

Mr Herbert, who owned the Llanarth and Llanover estates, was best known as a financier and gardener whose drive and vision transformed the Royal Horticultural Society in the late 1980s, opening its expertise to a wide public, restoring its finances and doubling its membership.

His interest in plants began young at his family home in Llanover, where the rare trees he grew from seed are now among the glories of south Wales.

He served Monmouthshire variously as High Sheriff (1972), Deputy Lieutenant (1968-99), Justice of the Peace (1964-74), Captain in the Royal Monmouthshire Royal Engineers (1962–68) and chair of the Abergavenny Rural and District Council.

Herbert’s many interests–in finance, business, conservation and horticulture–called him frequently away, but he was always closely involved in the Principality, playing key roles in the Campaign for Protection of Rural Wales, the Welsh Development Agency and the National Trust for Wales (Chairman 1969–84).

He was particularly proud of his role in the National Trust’s acquisition of Erddig, a much-loved 18th century house, garden and estate in Clwyd, notable for the documentation of the below-stairs staff and estate workers: he also helped the Trust–whose activity in Wales had been limited–with the Pembrokeshire Coastal Path; Chirk Castle, near Wrexham; and Plas Newydd on Anglesey.

As deputy chair of the Countryside Commission (1971-80), under the leadership of John Cripps, he fought to turn the Cambrian Mountains into a National Park: the Secretary of State for Wales, Peter Thomas, blocked the move in 1973, telling them his decision was political: “I cannot envisage any evidence which would lead me to change my mind.”

Herbert was not impressed, later observing: “You can never trust governments: their thinking is so short term that they miss the bigger picture.”

he himself could never be accused of missing the big picture; his extraordinary height–6ft, 7 inches–enabled him to see further than most ordinary mortals, while his attention to detail and belief in consultation and setting out clear aims before action won him a well-earned reputation for foresight.

Herbert was forced to think ahead while scarcely out of childhood. At the age of 13, he inherited 3,500 heavily indebted acres around Llanover.

His father Sir John Herbert, Conservative MP for Monmouth and Governor of Bengal, died in Calcutta in 1943 and his mother four years later.

From his twenties, Herbert determined to pay off the debts and improve the condition of the estate: to this end, his American grandmother, Lady Herbert, encouraged him to add a MBA at Harvard Business School to his Eton–Royal Horseguards–Oxford education.

He returned to Wales in 1957 with a suitcase of seed-cones from California’s Redwood forests, which he planted in the park at Llanover: they are now 2 acres of prize-winning Sequoia Sempervirens, each the height of Nelson’s column.

In 1960, he married Margaret Lewis, with whom he had four children before divorcing in 1988.

After a stint as an analyst in New York, Paris and London, he joined a consortium to buy a small merchant bank, Leopold Joseph, whose clients included The Rolling Stones and Cat Stevens.

By 1978, Herbert was chairman and much in demand as an advisor across the City: he joined the boards of the National Westminster Bank, Marks and Spencer and Consolidated Gold Fields.

In 2004, supported by his second wife, Philippa Hooper (née King), he steered Leopold Joseph to a sale to the Bank of Butterfield. It was, wrote The Financial Times, the “end of an era”.

Back in Wales, Herbert inherited another substantial agricultural estate, Llanarth, after the death of his father’s cousin, the Hon. Florens Roch in 1969.

Where others sold cottages, he improved them. He invested in farms, woods, rivers and people.

In 1973, a BBC journalist libelled him by suggesting otherwise: Herbert was awarded a significant sum in damages, which he donated to the National Trust.

For the Queen’s Silver Jubilee in 1977, he planted a mulberry or a walnut tree in every garden on the estates.

From 1999, when he handed the care of Llanover–and its prize-winning flock of Black Welsh Mountain sheep–to his daughter, Elizabeth Murray, he created a new garden with Philippa around their home in Llanbedr, Crickhowell, 800 ft above sea level.

Robin Herbert leaves five children: Elizabeth Murray and Ben Herbert live in Monmouthshire; Susannah Ford in London; Richard Herbert in New York and James Hooper in Gloucestershire.