This is a Hamilton Irvine Box. It is a suprapubic urinary drainage system.
Invented by Hamiton Irvine in the late 19th century at St Peter's Hospital, this one is from the Addenbrooke's collection.
Suprapubic drainage was usual after open prostatectomy and, later, after TURP.
This type of collecting apparatus was used by Sir Peter Freyer following his famous prostatectomies; he mentions it in his book.