There is a new YouGov poll for the Sun showing the Conservatives hitting a recent record high of 42% after the budget:
Conservative 42% (up 2%)
Labour 34% (up 2%)
Lib Dem 17% (down 1%)
The YouGov data shows the Tories at 41% before the Budget and at 42% after, although the difference is within the margin of error. The pre-Budget poll findings were Conservatives 41%, Labour 33%, Lib Dem 18%.