Recorded January 1954, released February 1954. Number 6 on pop charts, number 7 on R&B charts. Personnel: Pat Best (baritone); Jimmie Nabbie (tenor); Danny Owens (tenor); Jimmy Gordon (bass). Pat Best sings lead on both sides. Besides writing "I Understand", he also wrote "I Love You For Sentimental Reasons."
Billboard review, 3rd April, 1954:
"I Understand" - "Warm and intimate ballad is arranged by a knowing hand. It shows off the Four Tunes to best advantage. This side may need only the slightest shove to get it off the ground. With the breaks it could build with the best of them. Bears close watching."
"Sugar Lump" - "Cute ditty, cleverly written, is awarded a bouncy and infectious reading by the group. A good, commercial waxing that could make some noise with energetic promotion."
The Four Tunes started as The Brown Dots, the group formed by Deek Watson when he left The Ink Spots. He eventually split with The Brown Dots who became The Sentimentalists and then The Four Tunes.
The full story is on Marv Goldberg's site here:
From 1946 - 49 The Four Tunes recorded for Manor and its subsidiary Arco, both under their own name and as backing group for Savannah Churchill. They switched to RCA, recording for them from 1949 until 1952, then joined Jubilee with whom they recorded until 1957.
Thanks to Joan K for the sound files and scans of "I Understand" and its B side. And of course thanks to Joan for the whole Jubilee vocal group series.