Thank you so much Chris for posting the cover of this wonderful book by the Brigadier!!! it brings back many fond memories (it seems I still owe you a photo, which I will get to in due course
. As I have mentioned, I have handled the M1912 British officers sword he carried in that charge, which seems accurately represented in the painting though the bowl is not visible, but the scabbard mounts are correct. This leads me to believe that accuracy was keenly observed, and knowing the stickler the Brigadier was, I have no doubt such a detail as lance pennons would have been noted had they been present and incorrect, in our conversations.
While pennons did seem to be 'parade' oriented in the images I have seen of these Indian cavalry in WWI and of that period, I do believe they were indeed mounted on lances in combat. I had never heard the item about them serving the purpose of collecting blood, and would presume this idea may present along with the purpose of fullers in blades being 'blood gutters'. While sounding feasible perhaps in limited degree, these observations seem more contrived in my thinking.
I do know that pennons were indeed attached in combat with lances as per accounts of Polish lancers in the Napoleonic period, and that these pennons added dramatically to the sepsis of wounds by carrying this obviously contaminated material into them. The morbid agony of this typically mortal penetration was heightened by this factor as described in accounts I have seen, and as a result , lancers when captured were summarily killed rather than being held prisoner.
In the dramatic charge of the British 16th Lancers at Aliwal in India during the Sikh wars, after the battle the pennons of the troopers were so encrusted with blood in the aftermath, that it became a long held tradition for these lancers to 'crimp' thier pennons in remembrance. While the blood on the pennons was clearly of thier opponents, the observance was for the decimated ranks and men they lost in that charge.
As with many, if not most, colonial circumstances, yes often obsolete and surplus weapons and materials did continue almost anachronistically in these settings long beyond the period of familiar use in original context.
It seems most of the issues regarding the British lances was availability of male bamboo, and presumably in India there were more ready sources.
The durability of the lance pennons however, may not have been sufficient to keep them servicable in these frontier regions, and having them mounted in the case of this time period may have been considered superfluous. I think more concern was to the actual purpose of the lance rather than the traditional presence of these probably unreplaced items.
As to the materials used, as far as I know most pennons are made of the kind of bunting used in flags, however one lance I had in blue and yellow (3rd Skinners Horse) was made of a dyed almost burlap material.
All the best,