£22 supply and install is a very cost effective price, particularly if it's a standard price across several locations.
£22 supply only is probably factoring in the cost of going through the hoops at tender stage: 66p for the lamp/bulb/light_emitting_thing, £1.50 postage and packing, £19.84 for the interminable method statements, risk assessments and responses to pointless questions prior to winning the contract, or not winning another contract somewhere else.
I'm going through the hoops with a non-MOD tender process now
