Utilize the input text as a context reference, choose the right relationship between Parcelforce and Royal Mail from the options. Options: product/material produced, manufacturer, distributed by, industry, position held, original broadcaster, owned by, founded by, distribution format, headquarters location, stock exchange, currency, parent organization, chief executive officer, director/manager, owner of, operator, member of, employer, chairperson, platform, subsidiary, legal form, publisher, developer, brand, business division, location of formation, creator.

The continuing downturn in letter deliveries pushed revenue in the company's UKPIL business - which operates in the UK collecting and delivering parcels and letters through the Royal Mail Core Network and Parcelforce Worldwide - down 2pc.

Answer: parent_organization