I'm trying to date a Victorian? male family portrait from the clothes worn. Any experts out there?

This is an oil painting of a man wearing an unfastened single breasted black jacket with wide lapels and brass buttons (can't see how many, I'd guess 3 or 4) over a single breasted cream waistcoat with lapels and with 5 brass buttons all fastened. He has 2 strands of a watch? chain from the centre button leading to his right under the jacket. A white shirt shows 3 studs down the front, visible above the waistcoat, linked with a thin chain. There could be a gem of some kind in each stud.

The bow tie is unusual, tied from black cloth running twice? right round the upturned shirt collar, about 7 cm deep, but the 2 ends seem narrower and are tied in a bow in front (i.e. so that the black bow is against a wider black background). On (his) left side the bow resembles a standard modern bow tie (but a bit wider) but to (his) right, sticking out of the centre knot is a single end coming to a point. His hair is long-ish, half covering his ears, parted on his right, and his face is clean-shaven. He is British, but there is a chance that he was a resident of India at the time.

I'll be really impressed if anyone can help me!