Thirteen years in I'm reading the autobiography, and the poem typed above isn't the same as the one I have read.
Here it is



The King, he went a-walking, one merry morn in May.
The King, he laid him down to rest, and fell asleep, they say.
And when he woke, 'twas even,
(The hour of magic mood)
And Bluebell, wild Bluebell, was dancing in the wood.

The King, he gave a banquet to all the flowers (save one),
With hungry eyes he watched them, a-seeking one alone.
The rose was there in satin,
The lilly in green hood,
But Bluebell, wild bluebell, only dances in the wood.

The King, he frowned in anger, his hand upon his sword.
He sent his men to seize her, and bring her to their Lord.
With silken cords they bound her,
Before the King she stood,
Bluebell, wild Bluebell, who dances in the wood.

The King, he rose to greet her, the maid he'd sworn to wed.
The King, he took his golden crown and set it on her head.
And then he paled and shivered,
The Courtiers gazed in fear,
At Bluebell, grey Bluebell, so pale and ghostly there.

'O King, your crown is heavy, 'twould bow my head with care.
Your palace walls would shut me in, who lives as free as air.
The wind, he is my lover,
the sun my lover too,
And Bluebell, wild Bluebell shall ne'er be Queen to you.'

The King, he mourned a twelvemonth, and none could ease his pain.
The King, he went a-walking a-down a lovers' lane.
He laid aside his golden crown,
into the woods went he,
Where Bluebell, wild Bluebell, dances ever wild and free.

Ballad of the Maytime. Agatha Christie