Hi Gary, just had a look and I have Adjutants Roll 28/02/1846 for the 31st Regt. of Foot at WO12-4688...I have no notes on the partial Nominal Roll, the NA number I have given may help you look in the correct area, good luck and let me know what you find.
The 31st Regt. returned to England, volunteers who wished to remain in India took the bounty and transferred to other regiments, there are few F surnames on the Loodiannah Memorial 50th Regt Foot, can be found at http://www.redcoat.info/sutinfz5.htm
, my Adjutants Roll for the 50th Regt Foot is WO12-6138.
Hope this helps.