Whilst working with local playgroups in the early 1970's, Mrs Diana Casswell first had the idea that certain children she was working with would benefit from adventure play. From this idea Diana Casswell, along with her husband Reverend Peter Casswell, set about starting the first adventure playground for children with disabilities outside of inner London.

From the beginning, a group of committed and experienced people joined the management committee to see the creation of ELHAP. The first major hurdle was to find a suitable site for an adventure playground and by 1976 negotiations had been completed with the charity Barnardo's for use of this site. Work to adapt it began immediately. A workable area had to be fenced off, structures and play facilities built and pathways laid. Indoor adaptations also had to be made including additional toilet accommodation together with provision for wet weather activities. In 1976 ELHAP opened, being well used from the start and as facilities and awareness grew the playground became increasingly popular.

ELHAP was the third adventure playground specially built for children and young people with disabilities. It remains one of only eight specialist adventure playgrounds in the UK.  Drummond Abernethy, with his wealth of adventure play experience, used to describe ELHAP as the "very best adventure playground for children with special needs".