Sorry Geo! Not your fault though, that resin seat harness is wrong!
No worry though, as it probably won't be noticed, even with the canopy and hatch open.
There were variations of the 'Y' tail strap, with the version as shown in Andy's pic, and the later version, where the two shoulder straps joined a single longitudinal strap, before attaching to the 'Bowden' cables. The MkIX would normally have the latter, if fitted with the later harness, but both could be seen.
It's very possible that whoever designed that resin seat, thought the straps were the same as in the Hurricane, where that extra, lower 'Y' strap arrangement is on the front side, passing through the lower slot in the seat, and anchoring behind it. Although there is a slot, on early Spit seats at least, it wasn't used, due to angles and attachment points, as the 'g' force generated by the angles of the straps, when used 'in anger' would break the pilot's back !