Just dipping about in a few primaries this morning, I can see that in addition to the loyal residues of sepoys from the three BNIs mentioned above, (a mixture of Sikhs and Hindus), there were also about 80 Sikh sowars at Chinhat. As far as I can tell they came from the 2nd and 3rd Oudh Irregular Cavalry, (which had mutinied of course, along with the rest of the Oudh contingent - 3 x irregular cavalry regiments, 10 infantry regiments and two regiments of military police or thereabouts), because their officers in the battle were Capt Forbes and Lt Hardinge, who I can trace to those two regiments. They routed from the field, but fled back to the city, so I presume formed part of the garrison subsequently. Their none too distinguished behavior on that occasion was in stark contrast to the loyalist sepoys who were reported as rather nobly leaving their own wounded behind, in order to assist wounded Europeans from the field. Maj Bruere, who gets mentioned in the document you sent me this morning, was the commandant (CO) of 13th BNI, so I presume 'Bruere's Sikhs' to be that part of his regiment that remained loyal. There are also slightly unclear references to the Sikh sepoys being separated out from the Hindus, some little while before Chinhat, so as to prevent their being tainted, but it is unclear which regiments are at issue - I think possibly not only the BNIs, but also perhaps some of the Oudh regiments - after all if there are Sikhs in 2nd and 3rd OIC, I don't see why there should not also be at least some present in the ranks of the infantry regiments. 7th BLC are also knocking about a bit, on the 'wrong' side, but I have a reference to a purportedly loyal residue of about 80 being sent home, because their officers were convinced that it was only a matter of time. I do not think that this is the same 80 from Chinhat: a. Because the BLCs were largely Muslim. b. Because I have a definite reference to Sikh sowars during the siege. c. Because I think the affair pre-dates Chinhat.
If I stumble across anything more clearcut and compelling, (which I doubt - at least not without a huge and potentially nugatory cross-referring exercise, conducted across the entire contents of my library), I'll be sure to let you know.
Dr Mike Snook MBE psc