What was the date of the 1948 Epsom Derby ?

My Mother-In-Law insists that the 1948 Epsom Derby was run on a Saturday as her friend got married the same day (June 5th). As far as I can tell, the Derby was always held on Wednesday until 1995. Was this year the exception for some reason, or did the Derby take place a few days before her friends wedding, which is the only explanation I can think of.