Although the film was reviewed by government censors, the participants obviously had no fear of lambasting the politicians.
1630s, from lam (1590s, ultimately from a Scandinavian source, cf. Old Norse lemja "to beat, to lame") + baste "to thrash" (see baste). Related: Lambasted; lambasting.
[1637+; ultimately fr British lam and baste, both ''beat'']