Thomas Tellefsen was a student of Chopin, and his works bear the distinct influence of Polish romanticism and Norwegian folk aesthetics. The piece is notable for its mournful, song-like quality typical of the mid-19th century elegy.
At Henle 4 this is an intermediate piece that expects secure technique and real attention to phrasing. The main demands: a true singing tone, with the melody floating above the accompaniment; rubato that must breathe naturally without losing the pulse; and big chords that need weight without harshness.
Beyond that, expect careful pedaling — clarity depends on the foot as much as the fingers.
Develop a warm tone quality to support the expressive, wide-spanned lyrical phrases.
Comparable difficulty and character — good candidates for what to learn next.
A level or two down with the same spirit — ideal if this piece is still out of reach.
Where this piece's skills lead: slightly harder works making similar technical demands.
Lesser-known works by the same hand, at a comparable level.
Elegy (Op.7) is rated Henle level 4 of 9 — intermediate repertoire, roughly ABRSM grades 5–6. In the RCM system it corresponds to about level 6.
You should be comfortable at Henle level 4 — meaning you can already play level 3–4 pieces cleanly. Learning it one level early is possible as a stretch piece, but more than that usually leads to months of frustration.
A typical performance of Elegy (Op.7) lasts about 4 minutes.
Elegy (Op.7) is available as free public-domain sheet music on IMSLP — the score is linked directly from this page.
Pieces at a comparable difficulty and character include Dans la Vallée, Idylle by Thomas Dyke Acland Tellefsen, Berceuse by Thomas Dyke Acland Tellefsen, Nocturne in C-sharp minor by Frédéric Chopin — see the full similar-pieces list on this page.