In the poem, he implies that her death in 1997 robbed the country of a future leader, despite her divorcing out of the Monarchy the previous year.
But luckily for Lewis, her greatness was such that her love still fills hearts to this day.
"England's beauty captured in one sweet soul, carried the torch - God rest her soul," he writes, before appearing to question the whereabouts of her remains.
"Hearts still full Of the love she gave, 20 years since she laid in her grave," he writes.
The Mercedes-driving three-time Formula One champion also shared a slideshow of his favourite Diana photos, set to Van Morrison's Into the Mystic.
The day before he posted a photo on Instagram of Diana, with one of her quotes: "I don't go by the rule book... I lead from the heart, not the head."
His poem follows mourners gathering yesterday at Kensington Palace, where butler Paul Burrell said he grew close to the princess.
The butler, famed for his interviews about royal secrets, recently appeared on Channel 5's In Therapy, where he spoke about Lady Di's 'soft warm corpse'.
'ENGLAND'S ROSE' - POEM IN FULL
The day we lost our Nation's Rose,
Tears we cried like rivers flowed,
The earth stood still
As we laid her to rest,
A day you & I
Will never forget,
The people's princess
Who came to see,
The love from a country
We'd hope she'd lead,
England's beauty
Captured in one sweet soul,
Carried the torch
God rest her soul,
With the gift she had
She'd light up the way,
With a smile to show us a brighter day,
Hearts still full
Of the love she gave,
20 years since she laid in her grave,
There will never be another like you,
Now a shining star in the midnight sky
I will always remember you,
Princess Diana,
As our sweet nation's rose
