Blue Letter - Why?

[squealy]

Does anyone know why Fleetwood Mac recorded "Blue Letter" on the self-titled album? Was it something the record company wanted on there? FM must have had plenty of original material. I don't think it's bad, but I can't imagine anyone in the band (least of all Lindsey) thinking it was so great that it would be worth doing instead of an original. It's just a generic piece of mid-70s light rock; any band of the time could have recorded it. What's the story?