I think your neighbour may be acting in contravention of the Household Food Waste and Bio-Waste Regulations 2013. Part III of the Regulations states:
SEGREGATION OF HOUSEHOLD FOOD WASTE
Producers’ duty to source segregate food waste arising as household waste
6. (1) Subject to paragraph (2) and without prejudice to the power of any local authority to provide for additional policy objectives under a relevant waste management plan or to apply more onerous conditions under a waste collection permit or under a waste presentation bye-law, an original producer of food waste arising as part of household waste shall ensure, as a minimum, that—
(a) food waste arising on the producer’s premises is source segregated and kept separate from non-biodegradable materials, other waste and contaminants; and
(c) source segregated food waste arising on the producer’s premises is collected by an authorised waste collector.
(2) Paragraph (1) shall not apply where an original food waste producer—
(a) subjects the food waste to a home composting process on the premises where the food waste is produced; or
(b) brings the food waste to an authorised facility with a view to its composting or anaerobic digestion or treatment in a way which fulfils a high level of environmental protection.
(3) Where an original food waste producer undertakes a home composting process he or she shall minimise the creation of odours and nuisance, and shall take all reasonable steps to achieve this objective.
Prohibition on certain practices
7. An original producer of food waste arising as part of household waste, shall not—
(a) deposit food waste in the residual waste collection, or
(b) use purpose built mechanical devices to shred or hydrate or otherwise alter the structure of food waste for the purposes of facilitating its discharge in waste water to a service connection, drain or sewer.
In other words, the person producing food waste must either have it collected, bring it to a recycling centre or compost it
themselves.
Local authorities have powers to act against any breeches of these regulations.