It is the southern terminus of the Butetown branch line 1 mile (1.5 km) south of Cardiff Queen Street.
For various reasons, including it being the origin of the first steam-powered passenger train service in Wales, the station is a Grade II* listed building.
The Victorian Society said the Bute Street station was one of the oldest and most significant railway structures in Wales and in the previous year appeared on its list of the 10 most endangered buildings.
It said it supported a sensitive restoration scheme but the current proposal would cause a "high degree of harm to the building and its setting".
In June 2018, the then future Welsh train operating company KeolisAmey Wales announced plans to build a line extension and a terminus station, The Flourish (since renamed back to Cardiff Bay) for the Butetown Branch, along with an intermediate station at Loudoun Square.