When William Bray toured the country in the late eighteenth century the road to Matlock Bath crossed "a little stream that comes from Bonsal in its way to the Derwent, which it falls into just below, after turning a mill for spinning cotton, invented by one Mr. Arkwright, who has a patent for it"^[1]. However, whilst the road into the Dale existed in Bray's time, it wasn't blasted through like this until 1815.

Reverend Ward described the view of Scarthin Rock in 1827. The lamp and the seat were not there is Rev. Ward's time, of course.

"The situation of Matlock Bath is in the bosom of a deep valley by the side of the Derwent^[2].
At its south end it is separated from the village of Cromford by an immense limestone rock called Scarthin rock, through one end of which the turnpike road has been formed by blasting the stone with gunpowder. It has often been mentioned with regret that, in doing this, the rock was not merely perforated, and a rude arch left over the passage ; since such a vestibule to the romantic dale would have been extremely appropriate, and have produced a very happy effect.
Upon entering the valley here, the eye is presented with a very striking view. The river Derwent, which flows through it with a southern course, here winds towards the east. Beyond it is seen a lawn; on the further side and on a very elevated part of which stands Willersley Castle"^[2].

We can see the Willersley boundary in the photograph — the stone wall is on the far side of the gap in the rocks — and Willersley Castle's lawn is visible in the distance. Road widening and improvements to the A6 in the early 1960's considerably altered the landscape when the sides of Scarthin Tor were partially removed^[3].

Rosemary Lockie has a postcard of the other side of the Tor, showing both the rock and Scarthin Lodge, on her Wishful Thinking site.
See "The Tors, entering Cromford."

There are several references to Scarthin Nick in early guide books:

• Moore's "Picturesque Excursions From Derby to Matlock Bath, 1818", pp.20-27 To Willersley Castle, and Through Matlock Dale. Read the first couple of paragraphs.
  
  
• Barker's "The Panorama of Matlock, 1827", Matlock Bath & The Waters pp.1-11. Read the first three paragraphs.
  
  
• Adam's "The Gem of the Peak", 1840. Present state of the Dale. In 1840 William Adam thought the Scarthin Nick was a "rocky barrier"^[4].
  
  

References:

^[1] Bray, William (1783) "Sketch of a Tour Into Derbyshire and Yorkshire" (Second Edition) London, Printed for B. White at Horace's Head, in Fleet-Street. The first edition was published in 1778.

^[2] Ward, Reverend Richard (Seventh Edn., 1827) "The Matlock, Buxton and Castleton Guide, containing concise accounts of these and other remarkable places ... in the ... County of Derby", Derby.

^[3] See both Road Widening at Matlock Bath, 1967 and Michael Fay's article "The End of a Long and Winding Road". Scroll down to the section called "Difficult civil engineering work" as there are several photographs of the junction at the beginning of the 1960s.

^[4] William Adam describes the Scarthin Nick as a "rocky barrier" - see Gem of the Peak (extract), 1840