A melody from a tomb stone...

John Benjamin Tolkien and his wife Mary are buried in the same grave with William Shrubsole, an English musician and composer of the hymn-tune "Miles Lane" (Tolkien Gateway). It was set to the hymn by Edward Perronet, All hail! the power of Jesus' Name. Shrubsole knew Perronet at Canterbury, and Perronet left him property. The first notes of "Miles Lane" were cut on Shrubsole's tombstone.

First, why J.R.R. Tolkien's great-great-grandparents are buried in the same grave with a Methodist composer? Second, what is "Miles Lane"'s melody? 

John Benjamin Tolkien's parents – Christian and Euphrosina – were probably buried in Gdańsk (Danzig), Poland (Gdańsk from 1793 and from 1817 was occupied by Prussia and its Tolkiens changed their family name into the germanized form Tollkühn). [in fact they were - they were buried at the cemetery of St Salvator, Petershagen/Danzig] So there was not a Tolkien family grave in England. Being buried with an English composer was probably an act of "adoption" of some kind. The first English Tolkiens were born as Lutherans in Poland but in England they became closer and closer to John Wesley – living still on City Road, London – and they are buried in the Methodist cemeteries (John Benjamin on Bunhill Fields "Nonconformist" cemetery, Daniel Gottlieb a hundred yards farther on the Methodist cemetery by the Wesley's Chapel on City Road). The Tolkiens' next generations were also Nonconformists – Methodists and Baptists [in fact Congregationalists], Mabel Tolkien being the first Roman Catholic in this family.

And what is the melody from the tomb stone of Shrubsole and the Tolkiens? Here it is:

And here:

All hail the power of Jesus' name!
Let angels prostrate fall;
bring forth the royal diadem,
and crown Him Lord of all.
Bring forth the royal diadem,
and crown Him Lord of all.

Ye chosen seed of Israel's race,
ye ransomed from the Fall,
hail Him who saves you by His grace,
and crown Him Lord of all.
Hail Him who saves you by His grace,
and crown Him Lord of all.

Sinners, whose love can ne'er forget
the wormwood and the gall,
go spread your trophies at His feet,
and crown Him Lord of all.
Go spread your trophies at His feet,
and crown Him Lord of all.

Let every kindred, every tribe
on this terrestrial ball,
to Him all majesty ascribe,
and crown Him Lord of all.
To Him all majesty ascribe,
and crown Him Lord of all.

(Alternate wording to the above verse)
Let every tribe and every tongue
before Him prostrate fall
And shout in universal song
the crownèd Lord of all.
And shout in universal song
the crownèd Lord of all.

O that with yonder sacred throng
we at His feet may fall!
We'll join the everlasting song,
and crown Him Lord of all.
We'll join the everlasting song,
and crown Him Lord of all.