Good old BBC! Illustrate an item on North Wales coast main line with a picture of a diesel entering Roman Bridge!
Seriously though, the current West Coast operator has invested significantly in procuring the new class 805 train formations which are bi-mode specifically for the Euston - Holyhead route so they can run eastwards beyond Crewe using overhead power rather than diesel traction for the whole journey. This may beg the question whether any real purpose would be served by overhead electrification of the coast line and the attendant capital and maintenance costs. TfW seem to have no plans for electric traction of any sort in this area so the electrification would only benefit the relatively poor West Coast service beyond Crewe westwards.