"The truth is simple. If all Lib Dem backbenchers vote against a Coaltion government proposal, even with Labour support, the government will still win the vote. ... It is only if more than 40 Conservatives vote against the government and Labour opportunistically agrees that the government might lose."This says more than is immediately visible. The fact is that the Tories have 306 MPs (John Bercow is the Speaker and does not count as a Conservative MP) which is 48 more than Labour. Since there are 57 LibDem MPs (and 28 other MPs) then it is possible that if all LibDem MPs vote with Labour that this Conservative government could be defeated. There are 650 MPs and, since the five Sinn Féin MPs do not participate that means a majority requires 323 MPs.
However, that is not what Redwood said. He said "If all Lib Dem backbenchers vote against a Coalition government proposal" There are 20 so-called "frontbench" Liberal Democrat ministers and ten or so junior ministers (33 LibDem ministers in total), so that means that there are only 24 backbench LibDem MPs, which means that there could never be a majority against the Conservative government (306 Tory MPs + 33 LibDem ministers is more than the majority of 323).
Basically, Redwood is pointing out the only reason why there is a disproportionate number of LibDem ministers - it is to guarantee a government majority. A lot of Tory MPs are still smarting over missing out of ministerial posts that they thought that were theirs, and this resentment will continue, but they will remain disappointed because Cameron cannot have fewer than 17 LibDem ministers (306 + 17 = 323) since that is the only way he can guarantee a majority.
Actually, I disagree with the assertion that 40 Tory MPs would have to vote against the government. That figure assumes that all LibDems would vote with the government (306 + 57 - 40 = 323, which is still a government majority), Cameron can only guarantee the LibDem ministers so that means that if 17 Tory MPs vote against the government it would lose (assuming 33 LibDem ministers and all the other 22 sitting MPs vote against the government). It is unlikely that 17 Tory MPs would vote against the government, but some could abstain. The number of "rainbow coalition" (without LibDems) MPs is 14 (SNP, PC, Alliance, SDLP), so added to the number of Labour MPs and the backbench LibDems gives a figure of 296. If 40 Tory MPs abstained then the government would have 299 (306 + 33 - 40). If 45 abstained then the government would lose. (This does not take into account the eight DUP MPs, if the Conservative cuts in Northern Ireland are deep then these MPs may well vote against the government, meaning that just 38 Tory MPs would need to abstain.)
It seems to me that the campaign against the cuts should concentrate on persuading 40 Tory MPs to abstain.