"The reality is, most of us will struggle an entire lifetime to resolve one or two main issues. Yoga is the most effective way I know to aid that resolution, but it’s no magic spell (though there is plenty of magic)."

The scene is a chaotic house in the Dublin suburbs filled with the cries of four little children. Born to a feckless father and an inept mother, they have been dumped into the care of their grandparents, who plainly cannot cope.

The year is 1940 and, desperate to reduce their burden, the grandparents arrange for the two youngest of the brood — twin brothers, aged six months — to be adopted by a trusted family friend from London.

The friend’s name is Pamela Lyndon Travers. And as the author of a popular new children’s book about a nanny with magical powers, the eccentric writer — who is unmarried and yearns for a son — seems the ideal person.

When she arrives, however, she blithely insists she can only take one of the twins and (having consulted her astrologer to ensure she has made the right selection) picks the first-born boy, the bonnier and more placid of the two.

The chosen twin, Camillus Hone, is duly whisked away to a life of wealth and privilege amid London’s fashionable literary circle. But his rejected brother, Anthony, is left behind in Ireland, to be foisted onto neglectful relatives.

Thus, on the whim of one self-centred woman, were two lives mapped out.