[1] By trade, he was a menuisier (joiner or carpenter), and is known to have contributed to the construction of a number of the alpine huts used at that time by mountaineers to reach more easily the high summits.

One British mountaineer wrote in detail about Rey's achievements in "Pioneers of the Alps" (1888)[4]: 133 His reputation as one of the first rock-climbers in the Alps, and the position he holds among other guides, are the result of his own aptitude and ability, the great enthusiasm he has for his profession, and the energy and earnestness with which he pursues it.The first offer that Rey received of a long-term engagement as a guide came only after he had reached the age of thirty, when Lord Wentworth retained him for the greater part of the 1876 climbing season, and for the subsequent two seasons.

However it was with two other clients, J. Baumann and John Oakley Maund, that Rey started to make his name as one of the most skillful and boldest rock-climbers in the Alps.

[5] Thereafter, Mont Blanc became an important venue for his mountaineering exploits, and he had many regular wealthy clients from across Europe, including Elizabeth Hawkins-Whitshed,[3] Paul Güssfeldt[6]: 194  and Prince Luigi Amedeo, Duke of the Abruzzi.

[7] In 1882, Rey was leader of a team that retrieved the bodies of Francis Maitland Balfour and his guide Johann Petrus, who together had attempted to make the first ascent of the Aiguille Blanche de Peuterey.

[5]: 133 Commenting in the Alpine Journal on the series of audacious first ascents and new routes that had recently taken place on the Aiguille Blanche de Peuterey, the soldier and mountaineer, J. P. Farrar, who was later to become president of the Alpine Club, noted:[9] The evolution of these expeditions, among the greatest ever carried out in the Alps, is exceedingly interesting, nor will the names of the greatest guides who rendered their employers such brilliant service be readily forgotten, least of all that of the Italian, Émile Rey, who played such a leading role in the expeditions of 1880, 1885 and 1893.Rey was married to Faustina Vercelin[10] and had sons Adolphe and Henri, the eldest, and a grandson, Emile.

At the summit they visited the new observatory which had been opened just a few months earlier, and enjoyed hot steaming coffee and toasted ship's biscuits in the company of the observer and his two assistants.

[4]: 133 Whilst in Scotland Rey also visited Edinburgh where he went to the top of Arthur's Seat, local tradition stating that before doing so he estimated it would take much of the day to achieve.

Writing in 'Pioneers of the Alps (1888) Cunningham, with whom he had made numerous alpine ascents over many years, wrote thus:[4]: 134 He always draws a most distinct line between those of the higher and those of the lower grades in his craft.

One morning, at the Montanvert, we were watching the arrival of the 'polyglots,' as an ingenious person once christened that crowd composed of nearly every nationality, who may daily be seen making their toilsome pilgrimage from Chamonix.

Among them was an Englishman, who had first provided himself with green spectacles, a veil, and socks to go over his patent leather shoes, and who only wanted a guide to complete his preparations.

'"Cunningham also noted how willing Rey always was to attend to his clients' needs first, rather than his own, whether more immediate needs in the hut following a long and very tiring day, or in being bold on the rock to ensure they would overcome all difficulties to attain their summit.

Although Andreas Maurer's own back was frozen hard to the ice-wall against which he leaned, and in spite of driving snow and numbing cold, he opened his coat, waistcoat and shirt, and through the long hours of the night he held, pressed against his bare chest, the half-frozen body of the traveller who had urged him to undertake the expedition.

[7] Rey was buried in Courmayeur, the form of his gravestone somewhat resembling that of the Dent du Géant, with an ice axe and rope hung over one corner.

Amongst the wreaths left at his funeral were those from some of the famous names in the annals of alpine mountaineering, including Katharine Richardson, Paul Güssfeldt and C. D. Cunningham, all of whom had climbed with this guide.

[1]: 232  In a short obituary in the Alpine Journal, Güssfeldt described Rey as "the great guide of Courmayeur [whose death] is generally felt as an irreparable loss".