Good songs, both of them. Thanks.

I think modern people spell it 'lilly' because they have seen the name of the famous pharm company, Eli Lilly, in print.
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Once I asked my voice teacher why I had trouble saying 'lily.'

She explained that there are two entirely different L sounds in
English. One is in front of the mouth, as in 'like.' The other is in the back, in in 'old.' She told me to pronounce both L's in the front. It helps.

I am convinced that the Welsh Ll as in Lloyd came about because people said the L as in 'old' and held it. Try it.