Market leader Tesco TSCO.L was again the best performer of Britain's big four supermarket groups, extending its run of market share gains. By James Davey LONDON, March 1 (Reuters) - British grocery inflation hit 4.3% in February, market researcher Kantar said on Tuesday, warning more pain for consumers was likely from ongoing supply chain pressures and the potential impact of the conflict in Ukraine. Apart from the start of the COVID-19 pandemic, when UK supermarkets cut promotional deals to maintain product availability, February's inflation rate is the fastest Kantar has recorded since September 2013.