CPI inflation rose to 4.5% in April, compared to 4% in March. This was a surprisingly big increase.
(Note: this means prices were 4.5% higher in April 2011 compared to April 2010.)
The rise is blamed on increasing transport costs and rising prices for alcohol and tobacco. In his letter of explanation for the continued failure of inflation to meet the Bank of England target, Mervyn King said it was also due to the "increase in VAT to 20% in January, higher energy prices and increases in import prices".
On the other hand, RPI inflation fell a little from 5.3% to 5.2%, indicating some weakness in the housing market.
Read more about it here: http://www.bbc.co.uk/news/business-13421614