The Office for National Statistics (ONS) said consumer prices index (CPI) inflation dipped to 2.4% in April, from 2.8% in March, as lower fuel costs and air fares pushed overall transport prices down for the first time in almost four years.
But the temporary dip in inflation triggered by weaker commodity prices will do little to ease the financial pain on households, with inflation expected to spike above 3% in the summer.
The pace of the fall surprised economists, who had expected CPI inflation to edge down to about 2.7% in April.
Howard Archer, economist at IHS Global Insight, said: "April's marked drop in inflation to a seven-month low of 2.4% is very welcome news, providing significant relief for both consumers and the Bank of England." But Alan Clarke at Scotiabank said while it was a "big downward surprise", much of the fall is likely to be temporary.
The Treasury said it was "good news for families and businesses", adding the economy is "healing".
The only notable upward effect came from food and non-alcoholic drinks. Prices rose by 0.7% on the month, compared with a 0.1% fall a year earlier, as farmers pushed through price rises after the freezing winter ruined crops.
CPI inflation fell for the first time since last autumn, but is expected to provide only a temporary respite for households as rising gas, water and electricity bills feed through to households over the summer.
At 2.4%, it far outstrips wage rises which grew at just 0.4% in the first quarter versus a year earlier. Inflation has remained stubbornly above the Bank of England's 2% target since December 2009.