Thanks for you interest and help, Monica.
I don't think that James Allan & Son Ltd, Bootmakers is what I am looking for.
Robert Allan's business may have been J & R Allan Ltd, described as silk merchants and drapers and also as a department store, which doesn't sound quite like a shoe store. The "R" could be Robert, but I have no idea who the "J" may have been. Robert Allan was described as a "Drapers Assistant" in the 1861 Census when he was still living in Nigg, so that ties in. He would have died sometime after 1909, the year he visited his brother (my grandfather) in New Zealand.
Hopefully these comments might be of help.
Jonathan