By Laura McGuire B&Q ownerKingfishersaw its profit plunge last year due to worse-than-expected trading at its French arm, Castorama For the full year, the DIY chain said adjusted profit before tax was £568m, in line with lowered expectations, but down 25 per cent compared to the £758m it made the year before. The retailer, fronted by Thierry Garnier, issued two profit warnings during the year as consumer spending declined and while sales in France and Poland were impacted by a “more challenging consumer backdrop.” Sales for the year in the country fell by 5.9 per cent, while they grew slightly…