A Bank of England 194? Ten Shilling note (Series A - red/brown)(Chief Cashier K.O. Peppiatt - serial J19D), uncirculated and in absolute mint condition could fetch anything up to £80 GBP. If it has been circulated but still in good condition, it might fetch anything from £30 to £65 GBP.
A reputable coin dealer will be able to give a more accurate valuation.