Higher UK postage prices are set to come into force in April - a first-class stamp will cost 46p. This is a record 5p rise in the cost of sending standard letters weighing up to 100g by first-class post. Royal Mail has also increased the cost of a second-class stamp by 4p to 36p. A first-class, large letter stamp has risen by 9p to 75p, and by 7p to 58p for second-class mail. Consumer groups reacted badly and the industry watchdog described the inflation-busting rise as 'disappointing'.