Tobias Matthay (1858-1945) was one of the most influential figures in twentieth-century piano teaching. Glorified by some and villified by others, he left copious theoretical writings which today are little studied by serious pianists and teachers.
Most of his professional life was spent at the RAM. He served as a sub-professor there from 1876 to 1880, and became an assistant professor of pianoforte in 1880, before being promoted to professor in 1884.
His orchestral works were all written between the 1870s and 1890s before he focused instead on piano technique and teaching. They include two symphonies, some concert overtures and several piano concertante works. They were all forgotten for many years, resurfacing at a Sotheby's manuscript auction on 30 November 2006, won by the Royal Academy of Music.
"In May" dates from 1883 but it had to wait until 1902 for it's first performance by the Bournemouth Symphony Orchestra.
There are no recordings of his orchestral music.
LINK: https://www.youtube.com/watch?v=UOcdViyXxMg
A reduced score of his 2nd concert-piece (A minor, Op.23) is available and both concertinos (D minor 1881/2, A minor 1895-1909) seem to be at the RAM in possibly full-score manuscript, but yeah...
WorldCat only lists D Minor Concert Piece as the one with full score available. I've mentioned this one to Darrel and Tsou Yan Jiet before and hoped they can consider doing it.
Op.12 according to the RAM catalog (which also has a Matthay scherzo for orchestra digitized and accessible from it...)