"Left-footed" explained

I encountered a new term while reading "Good Omens" yesterday:

"He quite liked nuns.  Not that he was a, you know, left-footer or anything like that.  No, when it came to avoiding going to church, the church he stolidly avoided going to was St. Cecil and All Angels, no-nonsense C. of E..."

My wife found an explanation in an old column at The Guardian:

Why are Catholics sometimes called 'left-footers'? 

The saying turns on a traditional distinction between left- and right-handed spades in Irish agriculture...

Most types of digging spade in Britain and Ireland have foot-rests at the top of their blades; two-sided spades have foot-rests on each side of the shaft and socket, while an older style of one-sided spade had only one. Two-sided spades may well have been introduced by the Protestant 'planters' in the sixteenth century. By the early nineteenth century specialised spade and shovel mills in the north of Ireland were producing vast numbers of two-sided spades which came to be universally used in Ulster and strongly identified with the province.

One-sided spades with narrow blades and a foot-rest cut out of the side of the relatively larger wooden shaft continued in use in the south and west. The rural population of Gaelic Ireland retained the Catholic faith and tended also to retain the one-sided spade and 'dig with the wrong foot'. 

In fact, the two-sided spade of Ulster was generally used with the left foot whereas the one-sided spade tended to be used with the right foot. Instinctively, the 'wrong foot' of the Catholics has come to be thought of as the left foot...

--Hugh Cheape, National Museums of Scotland, Edinburgh.

The best image I've found of such a shovel in use is this one, from Jim Orr Photography -

- of a "loy spade" (from the Gaelic word laí, for spade).  His gallery of photographs of the shovel in use includes a closeup of the narrow-bladed tool (about half the width of a conventional shovel).

Top two photos from here (this one appears to me to be designed for use with the right foot) and (cropped from) here.

Addendum:  A tip of the ushanka to reader Aleksejs for finding the following explanatory video:

YouTube link.

I'll bet the ancient Irishmen would have loved to have had someone attach bicycle handlebars to their spades.