Voltage Operated Earth Leakage Circuit Breaker BS842
If you have a Voltage Operated Earth Leakage Circuit Breaker your house is due for a rewire but if you cannot afford a rewire you should at least replace the Voltage Operated Earth Leakage Circuit Breaker with an R.C.D. as it is more reliable and much safer or you could Replace the Fuseboard with a Consumer Unit that has R.C.C.B.O. instead of M.C.B. or fuse wire this is cheaper than a rewire and more reliable than a single R.C.D.
You will have a Voltage Operated Earth Leakage Circuit Breaker if you have an Overhead Supply This was a Requirement of 15 Edition IEE Wiring Regulations. till 1981, when it was superseded by the R.C.D. (BS7671 16 Edition of IEE Wiring Regulations) as it was much safer.
If you want to be safe you should contact your supplier and get your supply changed to P.M.E. and get an Electrician to change your Fuseboard to a Consumer Unit with R.C.C.B.O.'s