Very rare. This suppressed issue was, according to Carroll, riddled with printing production faults. The illustrations were over-printed, the pages badly folded and it led to him threatening to terminate his contract with publishers Macmillan:

‘the book is worthless… much as I should regret the having to sever a connection now lasted nearly 30 years, I shall feel myself absolutely compelled to do so, unless I can have some assurance that better care shall be taken, in future, to ensure that my books shall be of the best artistic quality attainable for the money’ (Letters p.995).

Only sixty copies had gone out when Carroll intervened. He asked Macmillan to destroy the remainder of the edition, which led to Through the Looking Glass being out of print until 1897. As mentioned in an ‘Advertisement’ inserted into the coeval edition of Sylvie and Bruno Concluded, Carroll later changed his mind about destroying the remaining copies of this edition, and instead favoured rebinding it and distributing it to charitable institutions, which had been done with the very first suppressed Alice, and as is the case with this copy.

Prior to this copy, there were sixteen known copies of the 60th thousand issue which went to Mechanics Institutes, according to the census compiled by Dr Selwn Goodacre a few years ago. Compared to other copies recorded, this particular copy does seem to be in superior condition.