Boron based compositions featured to a lesser degree in defence formulations developed by the MOD principally from the early 1950's through to the mid 1960's. The high cost of the element presumably precluded it from use in any area where common sense economics had any influence. The mixtures from memory and experience were used in primings, developed at Woolwich and later Fort Halstead they were listed in the low numbers of the SR register from SR 41 to SR 44. Further entries up into the SR 90's reveal the continued use of Boron but with other oxidising agents and almost exclusively in delay compositions - these entries relate to delays, either gasless or near gasless
For the nostalgic of us all, they really do hark back to a golden age where they competed with bakelite for inclusion in the approved materials list.
The compositions were employed in high altitude functioning stores. Besides one "prick sensitive composition" I never recall these being that exciting - other than to the purchasing department!, I rescued the last of the stock from the bonfire before Astra disappeared - came across it a little while back with notes I made on the label at the time "washed and dried". At a fraction of the price R.O. / MOD favoured Silicon having explored throughout the same period Zirconium (£!!) and various oxidising agents.
Safety certificates were issued which did not make for exciting reading, depending of course on the choice of Oxidant - as I write this I am reading the entry on SR 61 which shows an F of I - 20-35 and F of F 100-100-60. Three Shredded Wheat before mixing that one maybe!