Here's the song Hartlake Bridge and background information, thanks to the Musical Traditions website:

12 - Hartlake Bridge (Roud 1729, MS 120)
Sung by Jasper Smith, Epsom, Surrey.

Now, seven and thirty strangers,
Oh, a-hopping they had been.
They were plied by Mr. Cox's,
Oh, near old Golder's Green
It were in the parish of Hadlow,
That's near old Tonbridge town.
But they heard the screams from those poor souls
When they were going down.

Now some were men and women,
And the others gals and boys.
They kept in contract [contact] with the bridge
'Til the horses they took shy.
They kept in contract with the bridge,
'Til the horses they took shy.
But they heard the screams from those poor souls
As they were going down.

Now, some were men and women,
The others gals and boys.
They was 'plied by Mr Cox's,
Oh, near old Golder's Green.
It was in the parish of Hadlow,
That's near old Tonbridge town.
That they heard the screams from those poor souls
When they were going down.

In October, 1858, during a violent thunderstorm, the river Medway burst its banks just south of the village of Hadlow in Kent. During the storm a wooden bridge was washed away at a time when thirty Gypsies and Irish hop-pickers were being driven across the bridge in a horse-drawn cart. The victims were later washed up at a spot called Golden Green and they are buried together in Hadlow Parish churchyard. It would seem likely that this song was composed shortly after the event. Although I had been told by older Gypsies that other verses exist, I was never able to find a complete version of the song. MacColl and Seeger recorded a two verse example from Nelson Ridley which has all the same detail, but correctly cites Golden Green, and names the bridge as Larklake Bridge. Joe Jones also knew a fragment and, like Jasper, used a tune that is also used by Gypsies for another song, Dear Old Erin's Isle. The Irish singer Tom Lenihan used the same tune for his song Farewell to Miltown Malbay and the notes to The Mount Callan Garland - Songs from the repertoire of Tom Lenihan (Dublin, 1994. pp. 17-19) mention that the tune was formerly used for the song The Felons of the Land.