Hi ,
The up an over folded foot was quite common in continental Europe in the 17th and 18th C,as yet i have not seen an early English glass with this feature , the up and over fold also re appeared in the late 19th and 20th c on both Continental and English items made in an 18th c style,talking to replica glass blowers I don't think anyone really knows why the up and over fold was used as it would seem to involve another step in the process of production.
I do have some early continental pieces with fold up feet ,but no pics handy.
cheers ,
Peter.