So Heaton is in esteemed company in this regard - fellow keeper Raimond van der Gouw came close to hitting 40 but made his last United appearance a little under a year shy.
In terms of the current Premier League, James Milner is still playing in his forties. The Brighton & Hove Albion midfielder, who could face Michael Carrick's Reds on the last day of this campaign, has recently broken the record for the most appearances in the division, surpassing Gareth Barry's mark.
The oldest outfield player ever to appear since the league was reformed in 1992 is our former forward Teddy Sheringham. The classy striker achieved the feat when with West Ham United, in 2006 (aged 40 years and 272 days).
Another ex-Red, Gordon Strachan, enjoyed six outings with Coventry City while in his forties. Kevin Phillips is the only other outfielder, other than those we have mentioned, to have been over 40 when appearing in the division.