Regarding the Paris in London Exhibition medal, there is a listing in British Medals Since 1760 by Col. M. H. Grant (originally run in serial form in the British Numismatic Journal 1936 - 41) under 1902: Paris Exhib., Earl's Court Anon.
While the medal appears to have been previously published, there is no new information to add.
I saw one other example, in silver, in a private collection some years ago. The medal is certainly very rare and escaped being listed by the late Leslie Allen in 2004 when he published all the different types of UK exhibition medals, 1840-1909, known to him. Spink produced several variants of medals for functions at Earls Court at the turn of the 20th century, so I suppose it is no surprise they got involved with this one.
Imre Kiralfy, who died in April 1919, was an entrepreneur of considerable note, as your correspondent says. He designed the White City stadium, venue of the 1908 Olympics. At least two medals awarded to his son, Gerald, have surfaced on the British market in recent years and one of them described Gerald as the Architect-in-Chief of the Japan-British Exhibition, 1910.