[didibus]

It isn't clear though if McCarthy didn't know anything about the Lambda Calculus, or simply didn't know it well and didn't create Lisp as a concrete realization of Lambda Calculus. In that, he might have created Lisp for whatever other reasons and was doing his own exploration, but it's probable that in doing so, he used his inherent knowledge of many pre-existing literature, which could include some of Lambda Calculus, thus Lisp having some resemblance to it, like the use of lambda to define functions.

Also, realistically speaking, no programming language is based on the Lambda Calculus as is, even those that try to be.