Business.How does one value for sale purposes a�10M order book for a private uk manufacturing operation.?

I am involved in the UK manufacturing sector and my company has ORDERS for �10million next year. We have been approached by an acquisative company wishing to consolidate the sector by purchasing order books from other manufacturers within the industry. The company is able to sell this order book and will not be affected by the diminished income this area generates. The orders can be fulfilled easily by another operator once the contracts of production have been exchaned and there is no reason why this order book would be �10 plus the following year. How would one place a ball park figure on its value? Please qualify your answers. many thanks. can i help you?