Thank-you for responding, Joe. So, I used the 'Create Feature Class' tool in the 'Data Management' toolbox to create a polygon feature and set the processing extent to 50 and 52 south and north respectively and -7 and 3 west and east in the 'Environments' window. I left all the other defaults as they were. The process ran and a shapefile was created, though, it did not produce a visual polygon on the map. I then used this file to clip my shapefile of the UK but got an error message that the output was empty (error 000117). Any idea where I'm going wrong?
Thanks so much!
Laura