Ashley used a reference document from Reaction Engines. The document is no longer available online.

Skylon remains uncompetitive when compared with even the partially reusable (let alone the fully reusable) Falcon rockets:

* Skylon costs about 30 times more than a Falcon 9 and 20 times more than a Falcon Heavy. While it is hypothetically more reliable (though I question this), such an enormous difference has a significant impact on insurance costs, which drives up operating costs further.

* Using an exotic and relatively expensive combination of jet and rocket propellants, it costs about six times more to refuel Skylon than a Falcon 9, and twice as much as a Falcon Heavy.