A release date of 7 Jul 1972 is given in booklet 'The New Singles' No. 432
A release date of 1 Jun 1973 is given in booklet 'The New Singles' No. 477
A release date of 17 Jan 1975 is given in booklet 'The New Singles' No. 557.
I appreciate that this is going back a year and a half to Burdockman's original comment, but I would say that the blue-and-yellow promo is from the first issue of this single, in July - other Spark promo singles from the period 7th July to 11th August have the same layout. The first plain yellow demos seem to have appeared in October 1972 and to have continued on into 1973. This suggests that the plain yellow demo was from a reissue, perhaps in 1973. If that is the case, that would point to the reissue having the same catalogue number as the original issue, rather than the SRL-1086 that the chap from Peer Music suggested.
I'm told by someone at Peer Music in London who own the rights to the music released on all the Spark 45's that this was re-released under the catalogue number SRL 1086 in 1973. Can anyone confirm this?