The pair spent six months trialling the food and drink at the airport's 73 restaurants and bars to understand the offering before giving their views on what could improve it.
Each year 26 million orders are placed through Heathrow's bars and restaurants, which include Rhubarb, Carluccio's, Wagamama and Tragus' Oriel brasserie, and, as our report from Heathrow last year shows, established operators are increasingly seeing the potential in having a presence at busy transport hubs.
While Heathrow's dining operations at Terminal 3 were recently overhauled and work is on-going to improve Terminal 2, Ben Crowley, head of food and beverage at Heathrow thought there was more that could be done to improve the offering.
"Heathrow's food and drink offering is designed specifically with travellers in mind - from people passing through several time zones in a very short space of time to those needing a meal in minutes," he said.
"We've been recognised on a global level but for us this is not enough. We want to continue to innovate to be the best in our league for airport dining. We are hugely excited about responding to the challenge John and Gregg have set and at bringing a new dimension to Heathrow food and beverage offering."
Following their gastronomic tour, Torode and Wallace asked Heathrow's food and beverage team to introduce healthier food choices across the terminals and create a platform to champion British culinary talent.
Their experiences have also been used to help produce a food guide for travellers through the airport. The guide - Food on the Fly - aims to give passengers an overview of the varied dining options available in the airport, from chain restaurants and pubs such as J.D Wetherspoon and YO! Sushi through to fine-dining options such as Gordon Ramsay Plane Food.
It will be handed out to 10,000 passengers to mark the start of the summer getaway while a digital edition will be posted on the airport's website in July.
Wallace said: "Food is our first love and at the heart of everything we do, so we were delighted when we were invited to take part in this eating challenge and to contribute to the guide. We were blown away by the range on offer to hungry passengers at Heathrow. Catering for such a huge spectrum of passengers is truly a herculean task."
Crowley added: "It's often hard to show passengers - especially those in a hurry - the full extent of our offering so it's very exciting to be able to work with John and Gregg to produce this really comprehensive guide. We not only hope it will help passengers better navigate our restaurants and bars but also make the meal they have before they fly one to savour."
Heathrow food facts and figures:
- Breakfast is the most popular meal of the day with 6.4 million croissants, 5 million eggs and 4.5 million rashers of bacon served every year.
- Seafood is also a popular choice of ingredient with 1.5 tonnes of caviar, 25,000 kilos of salmon and 240,000 oysters served annually.
- The airport pours 800,000 glasses of Champagne every year.
- 630,000 steaks and 250,000 portions of sushi get dished up every year.