David Cameron certainly did not expect 30 members of parliament (MPs) from his own party, the Conservatives, and nine MPs from its coalition partner, the Liberal Democrats, to help defeat his motion for military intervention in Syria - the first time in recent history that the House of Commons has blocked the government from launching military action.
It was a huge blow to the UK prime minister, but given the shaky coalition with the Liberal Democrats, the lack of support from the ultra-conservative UK Independence Party (UKIP), and with public opinion largely against an intervention in Syria, it wasn't altogether surprising.
"It was, frankly, unbelievably poor parliamentary management on the part of the coalition government, to have gone into this vote without having it absolutely nailed down," Richard Whitman, Professor of Politics and International Relations at the University of Kent, told DW.
Just why Cameron pressed for the motion to be passed through parliament so quickly, Whitman says, and before the UN inspectors had reported back on the use of chemical weapons in Syria, remained a mystery and MPs from his own party, the Conservatives, agree.
"The West made great play of getting weapons inspectors into Syria. At the very least, we should give them time to report back," John Baron, one of the Conservative MPs who voted against the motion, told DW.
While France was quick to step into the breach and assure the US that it is "ready" for intervention in Syria after Thursday's UK 'no' vote, British Prime Minister David Cameron is scrambling to save face by insisting the UK was still seeking a "robust response" in Syria and was still "deeply engaged" on the world stage.
But Cameron seems to have failed to gauge the shift in attitude towards military missions among lawmakers in Britain.
"I certainly think Iraq has cast a long shadow. The threshold for military action has certainly been raised quite a bit. And I think that No. 10 [the government] miscalculated the extent to which that threshold has been raised," Whitman said.
"The tragedy is it's going to complicate British foreign and security policy in the short term," he said. "Because what is Britain's position on Syria now?"
According to Whitman, at one point, it was all about lending support to the Syrian rebels, now the UK seems to focus purely on punitive action against Assad - the latter made more difficult by the fact that Assad's air defence systems are much more advanced and have a much wider reach than, say, Libya's.
And that's what Baron and other MPs as well as military officials are concerned about - prolonged military engagements with no clear objective or strategy beyond mere punitive action, particularly if there is no legitimization in the form of a UN mandate.
"We cannot keep riding roughshod over the UN," Baron told DW. "It lessens our authority when, perhaps in future, we may have to condemn similar actions by countries less friendly to the West."
Britain's traditional "special relationship" with the US is also likely to be damaged by the negative vote, but Whitman acknowledged US-UK ties have been rough around the edges for some time.
"The relationship between the US and the UK was undergoing a recalibration anyway, ever since Iraq - the circumstances of Britain withdrawing from Iraq, the US thought it was premature," Whitman told DW. "So, it [the Syria vote] wasn't a watershed."
Rather, it's several issues accumulating to sour relations in the long term. Britain's involvement in Afghanistan has also been seen as problematic in the US, Whitman pointed out, and reducing British defence expenditure has not helped either.
"But also the strange position the UK finds itself in the EU now, with ambiguity to what its future relationship there may be, all that has accumulatively complicated the UK's relationship with the US."
What next for the EU?
And indeed, the handling of the Syrian issue could prove a pivotal moment in European foreign policy, as the US and France will likely try to recruit new allies, such as Poland, Whitman said.
"It will be interesting to see what kind of political coalition France will be able to pull together within the EU and where the UK stands within that coalition."
Another rebel Conservative MP, Crispin Blunt, who also voted against the government's Syria motion, thinks that UK foreign policy needs a major rethink.
"It is possible that last night finally saw the United Kingdom moving to a foreign and defence policy which is much more appropriate to a country of our size," he said in a statement to DW.