This British patent was cited in: Merrell Dow Pharmaceuticals Inc. and others vs. HN Norton & Co. Limited, United Kingdom House of Lord Decisions  UKHL 14 on 26th of October 1995. Thank you.
This was annoying to search for as the company cited as Merrell Dow didn't have any relevant patents dating back to 1972. No doubt this is because company names often change over time especially after mergers. The closest thing I could find for a UK patent application is GB1412605A. The assignee for that application was Richardson Merrell Inc. and the inventor was Albert A Carr. I think you'll likely find the patent of interest among the results of this search.