The reply might well have read as follows:

16th March 1864

Mr C.Dickens, Esq.

Honoured Sir,

I wuz greatly distressed by your hintimation that all is not well wiv your noble chimbley after hit ad received my hattentions.
I shall immediately send Arry, my best climbin boy, oo is well acquainted with the fell ways of chimbleys.
I would respeckfully arst you ter make sartin that no lidies is presint on that occasion, as the hintercourse between climbin boys and their chimbleys can oftimes be arsh.

Your hobediant sv’t

Alf. Doolittle
Chimbley Sweep
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I'm immortal until proven otherwise