I have picked up on old British postcard that was sent in 1935 and it shows the ‘Blackpool Monster’ and I have no idea what the card is about. An internet search only bought up a similar question but he called it the Mossog Monster of Blackpool. I did find their used to be a Monster Ride at Blackpool but I expected it might have been named after the monster not vice versa. Here is a photo of the card Also, people feel free to talk about any cryptozoological creature that are said to exist in your part of the world.
My best guess is that it's not based on an actual creature as such but was rather something done for the Blackpool Illuminations that year.
Yes, I thought it might be something to do with the illuminations when I read about them but then only a few minutes ago I came across this picture and the caption states https://www.flickr.com/photos/carlart/5432136446/in/photolist-9h27UW
It's obviously just a thing to encourage tourists as apart from the lights, Blackpool is a dump by all accounts.
Looking at the back of the card it looks like that the sender could have gone down to look at the Illuminations as I suppose they would have been also held in September in 1935.
I actually just found a short clip of the lights in 1935. It is hard to tell if the monster is there or not. I did not know about the existence of the illuminations until about an hour ago.
It won't be the related to the monster ride, that was opened in 1968 and was octopus themed. I'm inclined to suspect looking at the pic that Nessie would have been the inspiration, as others have stated. That being said, there are that many transient attractions throughout the town it could literally have been anything. Sorry!
There is nothing of special interest in Blackpool and yes it's a bit of dump, but then again being local(ish) to Blackpool I can go anytime and when things are on your doorstep anything special about them means less to you.