P clamp; I thought so too but when fitted to a pipe there still is a gap of 23mm / 1 1/8" between the tongs .
On the offside the bracket/lug does not have that size and on the nearside the bracket is a 'U' shaped flat bit.
That wont work.
I am guessing now that it could be for a upswept pipe on the saddle spring bracket with the distance piece that goes under the spring in between the two tongs of this P clamp, just a wild guess…
the one in the middle looks like it, ...almost.
So it most likely is the one that fixes the downpipe to the frame, but it wont fit on my two rigid frames .