The 'Shape of You' hitmaker treated the 69-year-old music legend to a Michelin star meal at the Welsh capital city's finest eatery, the Park House restaurant, costing £29, after playing his second sold-out concert at the nearby Principality Stadium.
Whilst Lionel enjoyed locally-sourced Brecon lamb, Ed chose not to eat and simply ''relaxed'' with a few glasses of 1997 Penfold Grange vino - which he'd seen on the menu before booking a table - until the early hours.
The pair had the full run of the oak-panelled 19th-century mansion's dining room and wine bar as the owners ''closed it off'' to the public.
Spokeswoman for Park House, Sian Gunney, told WalesOnline: ''Ed obviously knows his wine.
''His PA rang and made the booking and Ed actually spoke to the staff himself.
''They were both so down to earth and relaxed, they didn't have a demanding list of things they wanted.
''Ed didn't eat, he must have been so pumped with adrenaline.
''But he must have looked at the wine menu before he came because he knew exactly what he wanted.
''He went straight to the wine bar.
''Park House is a family-run business and everyone was so excited when they found out, but they were so professional the entire time.
''They wanted the guys to have a relaxed experience.
''Staff closed off the restaurant to the public so they had the restaurant and wine bar to themselves and even had a tour.''
The 28-year-old pop star had shared a photo of the pair standing on the steps of the restaurant on Friday (22.06.18), with a bottle of the fine wine in shot.
Alongside the picture, Ed wrote: ''Lovely dinner last night with this fine chap.''
The pair were no doubt discussing their forthcoming collaboration.
The 'Hello' hitmaker revealed at the Ivor Novello Awards in London last month, that he has asked the 'Lego House' singer to go in the studio with him and record a track after they hit it off at the awards ceremony - and that they were going to make it happen around their tours.
Talking about himself in the third person, Lionel said ''The next big project for Lionel is - I shouldn't say too much - but it involves Ed Sheeran. I was a little dumbstruck meeting him tonight. There's Ed over there and he's looking at me and I'm looking at Ed. It's a mutual admiration society. The first thing you say is, 'Do you think you might want to . . . ?' And the answer was, 'Of course.' He's on tour and I'm on tour but it will happen.''
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