This poster announced the concert at Leicester Polytechnic of Saturday 4th May 1974.
The design was done by a graphics student at Leicester Polytechnic, it was applied to all concerts of this period and was known as the 'Angels' design.
"Leicester Polytechnic presents | in Concert | Halcyon and John Martyn | 80p with N.U.S. in advance | £1 otherwise | 4 May at 8pm | Hawthorn Hall | R.O.A.R."

Hat tip Andrew Taylor