Great Britain 1988 13p Christmas error, SG1414aGreat Britain 1988 13p Christmas error, SG1414a. A very fine unmounted mint, with full original gum, example of this rare and most desirable 13p for 14p error of value. The 13p 1988 Christmas error has an interesting story behind its existence Production was in full swing for the 13p second class stamp in the run up to Christmas when the government decided on a Scrooge like rise in the rate to 14p. Wanting to take advantage of the increased rate, the