Why can't I see my template in the Page Template dropdown within admin?

I have created a base.html.twig inside the templates/partials/ dir, then a post.html.twiginside the templates/ dir.

This is the content of post.html.twig:

{% extends 'partials/base.html.twig' %}

{% block content %}
  <article class="c-main-content  c-post">

    <header class="c-post__header">
      <a class="c-post__permalink" href="#"><time datetime="{{ page.date|date('c') }}">{{ page.date|date("d/m/Y") }}</time></a>
      <h1 class="c-post__title">{{ page.title }}</h1>

    <div class="c-post__body">
      {{ page.content }}


{% endblock %} 

Can anyone shed any light on why this won’t show in the admin area? All I see is Default, Error and External.

Never mind - the file was named post.twig.html rather than post.html.twig. :unamused: