So it was bought in 2012 of £795k and is for sale for £1,195k. The original plans look quite grand and make more sense, but I couldn't see a planning application for what they actually did. Are you not obliged to build what you say you are going to build?
Unless I am missing something quite crucial, the changes made to the property don't feel to add up to the change in value suggested by the price it's up for (even allowing for profit and offers below the asking price).
It also seems odd that they moved the front door given that they didn't move the staircase as the "hallway" becomes awkward and by not moving the staircase they effectively lost a bedroom as they had to use one for the staircase to the second floor.
It all feels like they got part way through a plan and lost their nerve.