As most readers will know very few Thameslink service on the Sevenoaks route are due to have first accommodation. So standard class ticket holders may occupy the first-class areas on the class 700 trains.
I have discovered that it would appears that the first-class accommodation on other Thameslink routes using the new class 700 trains has been provided in excess of requirements. Only the first-class area at the front of the trains is being used for first class ticket holders. When the first-class area at the rear of the trains can be used by standard class ticket holders this can be identified by the platform information screens showing “first class is available at the front of this train”.
Occupying the first-class areas is the only way to have a comfortable journey on a class 700 train!