Yes, it is possible to use a Barclays mortgage for over 70s to release a lump sum of money. However, much like other types of mortgages, this should also be done with caution as the terms and conditions associated with the loan may be different from those of a regular loan. For instance, interest rate charges could be higher due to age-related risks involved. Additionally, some lenders might require additional documents or information before approving your application. Therefore, it is highly recommended to seek advice from an independent financial advisor before taking out any loan in order to fully understand all the details and make sure that everything goes smoothly.