Harry Lamb, 58, of Stirling Place, Brighton, said: "The theatre used to be owned by this slightly eccentric millionaire, David Land.
"He gave Andrew Lloyd Webber and Tim Rice their first break. On the walls of his private office he had gold and platinum discs for sales of Joseph and Jesus Christ Superstar - the soundtrack albums.
"He said one of his unfulfilled ambitions was to start a business called Hope and Glory, so that when he answered the phone he could say "Land - of Hope and Glory."
Harold Tayor, from Nottingham, said: "I can remember going to the Theatre Royal Brighton to see Ingrid Bergman in the early part of 1973 or 1978.
"She was a star like you don't find anymore."
Brian Murray, from Brighton, said: "We have attended the theatre for about 40 years and feel it is a pity that there has been no mention of 'Hazel' who for many years played a piano in the pit in front of the stalls before the performance began and again, we think, during the interval.
"It made a very pleasing and rather gracious contribution to the ambience and we still tend to miss her playing in the many years since she stopped or possibly was stopped."
Sue Anderson, from Haywards Heath, said: "I remember my first visit to the Theatre Royal, sometime between September 1963 and July 1966, as part of a school party from Cuckfield County Secondary School. We had seats up in 'the gods' and it felt like I was falling into the cauldron.
"I already had a love of books and reading, now I became hooked on the theatre. I am still hooked to this day.
"Happy Birthday Theatre Royal, long may you reign."
Ann Grant, from Australia, said: "In my early childhood my parents had the same seats booked on a regular basis and though very young at the time I remember The Wizard of Oz and Petula Clarke when she was still a child.
"It was an iconic time."
Bob Moulton, a retired local government officer from Ditchling, said: "It is the most reputable theatre in the area and we come here around a dozen times a year.
"They get some good stuff straight from London and we watch all types - anything from Shakespeare to comedy to fun events like the Rocky Horror Show."
His wife Diane, a retired teacher, said: "We came to the Rocky Horror Show last February when it was absolutely freezing and as we got out of the car there were these two guys in high heels and fishnets going, 'How does anyone walk in these things.' It was such an event. I dressed up in a long PVC mac and everyone really went for it."
Shineen Galloway, a retired company director from Heathfield, said: "It might be quite a drive but this is the best theatre in the area and it is worth it. There's nothing at like it in Heathfield.
"I do the drive so often the car knows its own way."
Richard Clarke said: "My memories of the Theatre Royal go back a long way, but my mother's - Edith Clarke's - went back a lot further. In the 1950s she and a neighbour would climb up into 'the gods', paying just a shilling (5p) to enjoy a performance every week.
"Her proudest memory came during the interval while she was watching a play in which Paul Scofield took the leading part. My memories are hazy, but I think it was Alexander The Great.
"A lady a little older than my mother sidled up to her and asked what she thought of the main actor. Fortunately my mother was a great admirer of him, as I myself have since become. She predicted a great future for him. He was not then as well known as today.
'I'm so glad,' the enquirer replied 'as I am his mother'. She apparently used to venture quite frequently into the upper circles to discover what the audience really thought of her son."
Paul Cook, 56, of Hove, said: "I come here whenever there is a play I fancy and always bring the grandchildren to the panto. It is a lovely old theatre and a good night out.
"The most memorable show I saw was Jeffrey Archer in The Accused - a play where his character was standing trial and the audience had to decide whether to find him guilty or not.
"It was before he was sent to prison himself which was quite funny and eerie at the same time."
Jackie Lythell, 73, has regularly visited the theatre as a member of the audience since she moved to Brighton in 1960.
The ex-deputy leader of Brighton and Hove City Council and chair of Brighton and Hove Arts Commission has seen a side of the theatre most people have not.
She was chair of the Brighton Philharmonic Orchestra when it performed in the theatre between October 1999 and March 2000 while the Brighton Dome was closed for refurbishment.
She said: "My first memory is watching Laurence Olivier in 'Dance of Death' during the early days of the Brighton Festival.
"It was an electrifying performance and one of the highlights of the festival that year.
"More recently, my favourite memory is going back stage with the orchestra.
"When the Brighton Dome closed down it was the orchestra's 75th year.
"It was devastating to have lost our permanent home for a while.
"But I get to see all those rooms behind the stage and was able to feel the atmosphere of nearly 200 years of theatre."