Gilpin Bank caves are the only ones around Morecambe Bay listed as explored by NLSC (so presumably North Lonsdale Speleo. Club) in 1967, but no reference:
https://northerncaves.co.uk/caves/details.php?id=2078
& also The Borehole, 1964 (although it appears to be before they joined NOLSPEC):
http://www.rrcpc.org.uk/easegill/text/Easegill_J4.htm