I am enquiring as to whether an NEC contract can ever be executed as a contract ‘under hand’, that is as a simple contract? My previous experiences working with NEC contracts have always been when an agreement was made under a deed.
It is entirely up to the parties as to how their contract comes into existence and what form it takes. It can be a simple contract, which can come into existence in many different ways in the UK: being signed by both parties, and by offer and acceptance. It can also come into existence by the use of a specialty contract such as a deed, in which case care will need to be taken as to its form.
If you are unsure about how to make such a contract we recommend that you get some legal advice on it.