How are the xls files created? What is the actual query you are using?
HiHi RoryA,
Xls files in question are created by our 02 remote field formations where they use Windows XP and Office 2003. About the 2nd part of your question, I have actually followed the Mike Grivin of Excelisfun Channel on YouTube's video "Highline Excel 2016 Class 21- Power Query Import Multiple Excel Workbooks with Multiple Sheets".
Tomorrow I shall try the technique suggested by Mr. Matt Allington and will update you accordingly.
Thanks for precious help.