I picked this up at COMPEX this weekend. It purports to be a privately rouletted R27a. It’s on piece, unfortunately not large enough or with any printing to provide context.

It appears that the upper left corner was severed by the diagonal cut exhibited by the underlying piece, and then reattached.

It’s not the first 1st Issue private roulette I’ve seen. I have an R5a that also is privately rouletted:

There is another rouletted R5a with a clean Philatelic Foundation Certificate:

http://pfsearch.org/pfsearch/pf_grd.php?calledfrom=lkp&btnSubmit=Search&appl_no=510290&certissued=&app_coufk=1&catnoselect=eq&certcatno=&pfoper=All&pfgrade=&certsymbol%5B%5D=All&subtype%5B%5D=All&certcolor=&keyoper=both&keyword=&recsperpage=10&pscolumn=default&sortord=DESC&calledfrom=lkp

Does anyone have any other examples, either plausible or implausible?