Conservatives have always been a movement crying out for a philosophy.
Conservatism is a party before it is a philosophy. Just as the Right contains many different people (including conservatives) with conflicting opinions, so does conservatism (a subset of the Right) also contain many different people with conflicting opinions.
The Conservative Party in the UK (and its predecessors) is regarded as a very successful political party, which has survived for so long by not having any principles.
However, the since the Conservative Party has occupied the niche of the right-wing party in the UK for many years, it has required a political philosophy to attempt to justify its existence and actions.
So what is conservatism? It is a political philosophy that thinks some things should be conserved. Which things? It is a political philosophy that thinks that change should be slow. Yet it does not oppose all change. So which changes are good, and which bad?
The reasoning behind conservatism is the law of unintended consequences. This should guard against being too convinced of your own rationality. ("The essential idea of leftism is that the world should be governed by scholars." C.f. the Cult of Reason.) A policy which appears to be good, on rational inspection, may turn out to have bad consequences on balance, because of bad consequences which were not foreseen by rationality. This has earned conservatism something of a reputation for disparaging rationality.
But how are we to judge policies except with the power of reason? Conservatism still cannot answer our question of what should be conserved; which changes are good? The law of unintended consequences should influence policy, but it is not a political philosophy.
Conservatism provides no long-term political direction.
In practice, conservatives are limited to trying only to reverse recent changes, or more usually to trying to prevent further change. They tend to accept changes as "inevitable" soon after they happen, and have a limited memory so tend to become happy with the change before last: they only want to turn back the clock a little bit.
Their mistake is to believe that they can stop the growth of state expenditure in a democracy, or that they can reverse social change without dominating the universities. With no long-term political direction, they cannot win.