The Judge, Mr Philip Richards, said the fire was a "very irresponsible act" with "consequences that were devastating". He acknowledged that Mr Goulding has considerable learning difficulties which is why he took so long to accept responsibility.
Mr Goulding has been remanded in custody and will be sentenced tomorrow at 2pm at Newport Crown Court.
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Watch: It's 1959 and Queen Street in the city centre still has traffic running through it and there are 'trolley buses" on the roads.
It will be mainly dry with sunny spells, the best of which will be in the south and east.
Almost 1,500 drivers made claims against councils across Wales for damage caused to their vehicles by potholes in the last financial year.