Yes, the illuminations are called the 'Venetian Nights'. The boats on the river are dressed up with lights.
Matlock (the town) and Matlock Bath (the 'seaside bit') became popular in the eighteenth century with the birth of tourism. There are springs at Matlock (like at Bath).
The dramatic scenery of Matlock Bath was likened to Switzerland and Italy, so for tourists it was a sort of fashionable East Midlands version of the Grand Tour.
I love it there, but the bikers are a bit of a nuisance. I never go at the weekend because of them