By inspecting the water-mark of the paper Lockhart discovered that 1805 was the period in which the first few chapters were composed; the rest of the paper was marked 1814.
Scott next observes that the unfavourable opinion of a critical friend on the first seven chapters induced him to lay the manuscript aside.

Who was this friend?
Lockhart thinks it was Erskine.

It is certain, from a letter of Ballantyne's at Abbotsford,--a letter printed by Lockhart, September 15, 1810,--that Ballantyne in 1810 saw at least the earlier portions of "Waverley," and it is clear enough that he had seen none of it before.

If any friend did read it in 1805, it cannot have been Ballantyne, and may have been Erskine.

But none of the paper bears a water-mark, between 1805 and 1813, so Scott must merely have taken it up, in 1810, as it had been for five years.