HTC’s latest flagship — the One M9 — has gone up for pre-order in the United Kingdom through retailer Carphone Warehouse and network operator EE.  While Carphone is offering the grey and silver models of the One M9 for pre-order, EE is offering an exclusive gold on gold variant of the handset for pre-order as well. Carphone has listed the SIM-free price of the One M9 at £579.99, along with the contract price of the phone under different networks. If you end up buying the phone on contract, the retailer will also give you a free Dot View 2 case to go along with it. As for EE, it is offering the One M9 across a range of plans with a minimum price that starts from £31.99/month. It is, however, recommending interested consumers in taking its £41.99/month plan under which they will get 1GB of 4G data, 1000 minutes of free talk time and unlimited SMS, though they will have to make a downpayment of £49.99 for the device. Both EE and Carphone Warehouse list 31st March as the estimated delivery date for the pre-orders.