Why RAF bombers were absent from the Taranto plan

Why did British plans for Taranto not include RAF bombers?

The planning began before suitable bombers could be assumed, and no RAF bomber squadron was based within useful range when the raid occurred.

The first British plan for attacking Taranto dated from the Abyssinian Crisis, when the later bomber force and its range could not be assumed. The same geographical problem remained when the carrier raid was carried out: no RAF bomber squadron was based within useful range. Adding land-based bombers would require moving a squadron and securing a suitable base before the operation. The plan therefore centred on the naval aircraft already able to approach and strike from a carrier.