Interesting thread as I started "hanging over the fence" at Squires Gate (Blackpool) around 1954 so I might have seen your mum loading one of the LAC Rapides. Rather ironically I still help out at Duxford loading the Classic Wings Rapides, one of which is G-AKIF which was owned by Manx Airlines from 10/47 to 10/58 and was a regular on the Blackpool -IOM service. I don't remember a seaplane service from Blackpool around that time and due to the nature of the beach at Blackpool I would think it rather unlikely. Happy Days though and the sun always shone!