Since Advent 2006 there has been a change to the holydays of obligation in England and Wales. Like Scotland, Ireland, Italy and most of the US, the celebrations of the Epiphany, Ascension and Corpus Christi have all been moved to the nearest Sunday. The bishops were concerned by diminishing observance of these days and wanted to maintain the rhythm of the liturgical year so that the mysteries of the Lord’s life were well celebrated by the faithful.
The others remain holydays as before: Ss Peter and Paul (29th June), the Assumption (15th August), All Saints (1st November) and Christmas Day. With the exception of Christmas Day, if any of these falls on a Saturday or Monday it is transferred to the Sunday.
Catechism 1163-1173, 2180-2183.