Also: 3.5 × 4.5 cm · 1.38 × 1.77 in · 413 × 531 px at 300 dpi · 827 × 1063 px at 600 dpi
•Recency window is 1 month - stricter than the usual 6
•Pure white is tolerated but degrades the GOV.UK automated checker's edge detection; grey or cream is safer