The origin and evolution of the large-scale structures in the universe (from galaxies up to superclusters) forms one of the outstanding problems of present-day cosmology. Several attempts have been made to observe the precursors of the structures observed today, at epochs as early as possible. Results of a search for redshifted HI associated with “protoclusters” or “pancakes” were first reported by Davies et al. (1978). They used the Jodrell Bank Mark 1A-telescope at frequencies of 328 and 240 MHz (z=3.3 and 4.9 respectively). More recently Bebbington (1986) used the Cambridge 6C synthesis radio telescope for a search at 151 MHz (z=8.4). Both experiments gave negative results and raised the question whether the observations were matched to the “expected” properties of the structures that they looked for.