Could Edinburgh's Castle Concerts stage a festival in a day?

Nipping down to London for the day, the vagaries of Sunday railway schedules meant I'd already missed a couple of acts by the time I arrived.

Openers Simply Red had been and gone so I never did get to discover if they are still holding back the years, and Kelsea Ballerini had already treated the gathering crowds to a Tennessee-tinged country set. Unapologetically, I’m glad I missed it. Country music being my thing.

Missing a 30 minute set from Bananarama (well two of them) didn’t seem like too big a hit to take either as it’s not that long since Edinburgh was treated to a full show from all three of them at The Castle - we’ll come back to the Castle Concerts, shortly.

Clean Bandit were in full flow as I settled in the press area behind the stage, where a giant screen gave a far clearer view of the scale of the event than could ever have been understood from the huge arena - 50,000 is a lot of people.

Clean Bandit, sweltering in unfortunate costume choices - the temperature peaked at around 74 degrees old money, that’s 23 degrees Celsius - nevertheless had the basking audience dancing, swaying and singing along to their classically infused synth-pop.

From the sublime to the vaguely ridiculous, Status Quo were next up. Any sense of irony may be lost on the old-school rockers and that’s not to say that Francis Rossi didn’t put in some hard graft, it’s just that since the loss of Rick Parfitt three years ago, Status Quo are just not the same.

Still, the anthemic In The Army Now with Rossi on vocals engaged while Rocking All Over The World closed a 50 minute set.

To the legend's credit, Rossi performed in the unexpected heat for almost twice as long as acts more than half his age.

Guitar riffs and drums beats were replaced a short time later by pop balladeers Westlife who, as the sun set, had the massive crowd holding their mobiles phone aloft, creating a twinkling sea of light in the falling darkness.

If Westlife only managed a 15 minute greatest hit set, headliners Pet Shop Boys had no such problems. With 42 Top 30 singles, 22 of them Top 10 hits, to choose from for their 70 minute performance (which included their brand new single Dreamland, bringing Years and Years’ Olly Alexander to the stage to duet with Neil Tennant), they were spoiled for choice.

That, by four songs in, Chris Lowe, the man who never smiles, was beaming all over his face tells you all you need to know about the reception they received.

Nearly four decades after they formed, Pet Shop Boys are still the Pop Kids.

The tag-line, ‘A Festival In A Day’, got me thinking: Would a day-long ‘Festival’ at Edinburgh Castle work?

Although, I admit, I’ll happily settle for Pet Shop Boys being one of this year’s Castle Concert series, after all, they are just about to embark on a greatest hits tour.

Perfect timing.

Watch BBC Radio 2's Live in Hyde Park on the BBC iPlayer

Could Edinburgh's Castle Concerts stage a festival in a day? - Liam Rudden