Allegations against Gregg Wallace are just the “tip of the iceberg”, a former MasterChef contestant has told Sky News – claiming he witnessed a “toxic environment” and was so “horrified” he considered quitting the show on his first day.

He alleged the “abuse” of contestants was widespread through the “production team”, but was too scared to speak out after signing a non-disclosure agreement.

The contestant, who did not wish to be identified, told Sky’s arts and entertainment…