Second hand prices in the UK and NI have risen even in the last couple of weeks so there is less price discrepancies now as to what there were, although some models will be always cheaper.
The second hand car market has picked up here considerably in ROI the past few weeks. Dealers are short good second hand stocks. I know of 5 people including myself, who have had their cars for sale for quite a while who have sold in the past 2 weeks.