Using Roud Numbers
The Roud Folk Song Index is a database of 300,000 references to over 21,600 songs that have been collected from oral tradition in the English language from all over the world. It is a combination of the Broadside Index (printed sources before 1900) and a "field-recording index". It subsumes all the previous well-known printed sources known to Francis James Child and more recent recorded audio sources from 1900 to 1975. Related songs are grouped under the same Roud number.
Taken from Wikipedia
Folkopedia song templates contain a linked reference to the relevant Roud Number. When clicked the link should lead to page which collects together all the songs in Folkopedia associated with that index number. See Roud 728 for an example.
This in turn should lead to the Roud Index search result on the Vaughan Williams Memorial Library site. Eg: Roud 728