Campaigners said a lack of an A&E department disproportionately affected older people and those without access to cars and left neighbouring hospitals struggling to cope.
Peter Cartwright, 82, suffered a heart attack three years ago and was taken to Wexham Park in Slough because “they would not take me to Wycombe as it was close to 20:00”.
He said someone he knew had died while being transferred to a hospital further away.
Another campaigner, Sarah Sturt, who lives with a chronic medical condition that sometimes means she cannot drive, said waiting for an ambulance to take her to another A&E department for treatment “could take days”.
She added that “if you are discharged in the middle of the night, there is no way home”.
Trevor Snaith, another Independent on Buckinghamshire Council, said the growth of Wycombe meant that having an A&E department “would meet the needs of a massive community”.
He added the issue had cross-party support on Buckinghamshire Council.
A spokesperson for Buckinghamshire Healthcare NHS Trust said a full A&E at Wycombe Hospital “would not be clinically or financially viable” as “it would require significant capital and revenue investment which the trust does not have”
They added that “it would be very hard to recruit the specialist staff needed” but “emergency services were best delivered through specialist centres supported by local urgent care”.