The blue-chip FTSE 100 index (.FTSE) ended 0.9% higher, while the domestically focussed FTSE 250 index (.FTMC) closed 2.8% up.
Both the indexes logged their third-straight day of gains, with the latter up more than 5%.
Under the new policy, most of Truss's 45 billion pounds of unfunded tax cuts will go and a two-year energy support scheme for households and businesses - expected to cost well over 100 billion pounds - will now be curtailed in April.
Register now for FREE unlimited access to Reuters.com RegisterHunt, who replaced Kwasi Kwarteng, said halting the planned tax cuts would raise 32 billion pounds ($36 billion) every year.
Traders are now seeing a 68.2% chance of a 100 basis points hike at the central bank's Nov. 3 meeting.