Make a comment with confidence and somebody might believe you. However, there's always someone who knows where to find the facts (even if they are only Wikifacts).
That first piccie on the right looks like a Siskin, is described as such and has the three Xs - the text tells us that 11 sqns were equipped with Siskins in the mid-1920s, and it would seem that 29 was one of them.
Sorry Haraka: Nope [what you wrote] it's simply not true.
I have heard the version about XX then one (I) X many years ago when I was based at Scampton on Vs during a visit (fughter affil debrief) to CGY. It sounds as plausible as any other.
Mister B