Hi
Thanks for the advice> I'll get a sparks to check the socket and plug. Although the plug is moulded so I'll have to cut off. I'll replace it with a good quality one.
Can I just ask ?

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Is it the moulded plug on the end of the factory supplied "Granny" lead that you intend to cut off and then hopefully replace here ?.
If correct, remember that solid moulded plug is manufactured that way for a very good reason.
Although it is not totally water proof, it does offers some protection against damp conditions.
Unlike a domestic three pin plug that is primary made for indoor use.
I think you may experience some difficulty making off that supply cable into the terminals in a standard 13 Amp domestic three pin plug.
It is going to get a bit busy inside the standard plug and you may get some trouble getting the strain relief strap in the plug, to accommodate the rubber supply flex.
It has been suggested that there could be a over heat detection facility built into the factory three pin plug, but I am unable to substantiate if this is true.
If this correct, then just cutting off the plug and replacing it with a standard good quality domestic plug top maybe a little unsafe.
If the Granny has worked fine for a good while, then suddenly failed due to the heat, my concern would be why did it suddenly happen and what was the primary cause of that excessive heat being generated ???.
The socket outlet and it's wiring has to be checked urgently.
At the very minimum the socket outlet requires replacing with a good quality unit.
I know the case for continued and long use of a Granny lead on a domestic supply will roll on for every really.
Plenty of owners rightfully claiming they have used a Granny lead for years on end and never had a problem.
Strangely not unlike yourself in fact, when suddenly out of the blue, this then happens !.
Heat is produced by a high resistance which builds up slowly over time.
What starts off by being a very slightly bad terminal connection, becomes more of a problem as a constant high load is drawn via that bad connection, which then becomes weaker and weaker over time.
The high resistance can cause arching and burning and there is then a real concern for a fire.
I was a Granny cable user myself for about six months, until having a wall box installed.
These units can suffer from similar problems if not installed / maintained correctly.
Termination points are the likely cause of problems as wall boxes are passing even more load than a Granny unit.
For this reason wall boxes are a stand alone device, they have one job to do ONLY.