This doesn't seem right to me for some reason.
With the exception of the Ypsilon and the Thesis, the other current and future Lancia models are based on platforms shared with Alfa Romeo and Fiat. If those models can be built in RHD and are able to be sold in the UK successfully, then why not Lancia? The engineering is already done for those vehicles utilizing common components -- what else is there that needs to be done outside of swtiching the dashboard layout?
Honestly, this is a bit shortsighted; especially as Fiat hopes to introduce Lancia into more markets. Already they are looking to sell the brand long-term in China, India, and other markets. Doesn't it make sense to push for expansion in the UK just as they tackle these markets?