At £1Bn, that's £14M per cab. That sounds not unreasonable to me just for the development/production cost, although it depends what avionics and weapons are spec'd. I'm not a Lynx expert, but other current RW are far more expensive.
When you add through life support, in all its guises..........
VAT? Spares? Wages? All stuff that has to be accounted for long before submission for approval, never mind contract award.
When discrepancies like this happen, the lower figure is often the marketing guy's rough unit cost to DEC, which is always VAT-Ex. Typically, DEC will forget/ignore that EP is VAT-Inc. They never make adequate provision for spares, repairs, training etc; and the concept of differing wage structures is, to be fair, detail which is best left to Commercial and Tech Costs. This is compounded by the Services no longer being required to quantify their requirements properly. (To cost, one must first quantify, but Ministers ruled this discipline as "unnecessary detail" some years ago). That's why many projects are over BUDGET, but within the FAIR and REASONABLE COST. If a project has been costed properly, it's odds-on the project manager has quantified it himself.
My guess would be the two questions were phrased differently (or imprecisely, which is common), and two different people provided what they genuinely thought were correct answers. Someone is stirring the ****. Hope this faffing about doesn't delay ISD.