A British 192? H.M. Treasury Ten Shilling note (green, purple, brown and white)(Chief Cashier N.F. Warren-Fisher - serial K58), uncirculated and in absolute mint condition could fetch anything up to £450 GBP. If it has been circulated but still in good condition, it might fetch anything from £50 to £250 GBP. A reputable coin dealer will be able to give a more accurate valuation.