It was originally designed by Henry Currey who was employed by the 7th Duke of Devonshire. Currey also designed the original College House for Eastbourne College, their Chapel and their Library, the Winter Garden and Pavilion, St Peter's church which is no longer in the Meads, and the Queen's Hotel on Marine Parade. So his influence is visible all across the older part of town and apparently lots of the windows and gables in Lower Meads reflect Currey's architectural style.
The Devonshire Park Theatre was first built in 1884 and was further improved in 1903 by Frank Matcham, a famous theatre architect. It closed for three months and re-opened to much acclaim having been beautifully recreated, redecorated, refurnished. Amongst other buildings, Matcham designed Blackpool Tower Ballroom and Opera House, the beautiful County Arcade in Leeds, Buxton Opera House and the Hippodromes in London and Bristol. In 1884, the theatre could seat 955 persons, now it is 936 and, occasionally, if you are very lucky (this is sarcasm!), you might attend a performance where every seat is sold! It makes for a fabulous atmosphere.
For those interested in a detailed history of this wonderful building and the shows it has housed, Friend of the Devonshire Park Theatre, Edward Thomas, has written a book entitled Playhouse on the Park. You can buy a new copy from the kiosk in the foyer or second-hand via Amazon.co.uk. It would make a good Christmas present for a theatre enthusiast!