Lynne, knowing it is George's birthday soon decides to go to a gift shop because there is no internet in the 70s and all gifts are brought at gift shops. However, this gift shop is ahead of its time, hence Lynne making a beeline for it, as it has a prototype for a mobile phone for sale. Granted this phone is the size of a grown woman's pelvis but it is pretty accurate in its design.
But the main point is, who does this woman assistant think she is? Her behaviour would get her sacked in a heartbeat. Not only is she willing to go on a date with a married man who she has never met, but she implies that she is beautiful and Lynne is not. Does this woman know of George (perhaps the town's foremost residential solicitor) or is she so desperate for male company she's willing to lose herself any chance of a sale by insulting the customers for the sake of a date with a man? This is an attractive woman, granted with no career prospects, but I think she could find a man of her own without resorting to this practice.
I'm guessing she hasn't met Harry?