What the specification means in practice
Two things about the UK specification surprise people who have applied elsewhere. The head is proportionally smaller — 29 to 34 mm inside a 45 mm frame, roughly 64% to 76% of the image height, where most ICAO-aligned countries want 70% to 80%. And the background is explicitly not white: HMPO asks for plain cream or light grey, precisely so that the edge of a pale face and pale hair stays distinguishable from it.
Printed and digital are different applications
The UK runs two parallel photo standards because it runs two application routes. A printed application needs two identical photographs measuring 45 mm high by 35 mm wide, printed professionally in colour on plain white photographic paper, with no borders, creases or tears.
A digital application needs an image at least 600 pixels wide and 750 pixels tall, with a file between 50 KB and 10 MB. The 600 × 750 minimum preserves the 35:45 proportion exactly, so a correctly framed digital photo can be printed as a correct paper photo and the reverse is also true.
The one-month rule on printed photos
Where most authorities accept a photo taken within the last six months, HMPO asks that a printed photo be taken within the last month. It is a stricter window than almost any other country on this list, and it is worth checking before you dig an existing print out of a drawer.
Choosing a background that is not white
HMPO accepts any plain background that is a light colour — different shades of white such as cream, ivory or vanilla, and light grey. A textured wall is acceptable provided the texture does not read as a visible mark. What it will not accept is a background with shadows on it, which is the usual failure when someone stands directly against a wall.
Because the acceptable range is broad, the practical test is contrast rather than colour: the outline of your head, including the top of your hair, must be clearly separable from whatever is behind it. Very fair hair against a cream wall fails that test even though cream is on the list.
Expression, glasses and headwear
A plain expression with the mouth closed is required. HMPO’s own examiner guidance is that a photo is rejected if the expression changes the shape of the face, which is a more useful formulation than "do not smile" — slightly parted lips that do not distort the face are tolerated.
Both eyes must be open and clearly visible, with no hair falling across them. Glasses should not be worn unless you have to wear them, and never sunglasses or tinted lenses; if worn, frames may partially cover the eye sockets but must not hide the eyes in any way. Hats and head coverings are not permitted except for religious or medical reasons.
Where UK applications usually fail
Shadows behind the head are the most common single cause, followed by head size outside the 29–34 mm band, glare on glasses, and hair across the eyes. On digital applications, a photo that has been cropped from a group shot often fails on resolution — cropping to a face from a wide frame rarely leaves 600 × 750 usable pixels, and upscaling to reach the minimum produces the soft, pixellated result the standard explicitly refuses.