Rubber cabling hasn't been used for fixed wiring for well over 50 years. Any that is still installed is decades overdue for replacement, as when manufactured it had a suggested lifespan of 25 years.
Each core is solid copper with a tin coating, hence the shiny silver appearance.
This cable would typically be used for lighting circuits, the twin red being used between a light fixture and switch.
There is no earth conductor, as earthing was not typically installed on lighting circuits before 1966.
Although these examples are in reasonable condition, this is primarily due to the ends only being exposed for these photographs. Typically the exposed inner insulation at the ends will dry out and crumble away to dust, leaving live parts exposed.
Any installations still in use which contain this type of cable should have already been replaced.