Originally Posted by Rocketpop:
“I briefly encountered something called 'the vodafone big top 40' countdown this Sunday on a local station while driving. What is this, and how is it different?”
The Big Top 40 has been going for years. It's basically commercial radio's equivalent to Radio 1's UK Top 40.
The only difference being the official chart moved to a Friday in July 2015 to co-incide with New Music Friday (oh, the irony considering how slow the UK charts have become ever since with almost no new music making the top 40 most weeks!!!

).
The Big Top 40 has remained as a Sunday afternoon chart show. Their chart is based on airplay for positions 40-11 whilst their top 10 is based on the iTunes top 10 for that afternoon. So those listening would've heard James Arthur at #1 as his new single was quite comfortably #1 on iTunes yesterday afternoon - and still is this morning.
Whilst it's not an official chart (and I've never actually listened to the Big Top 40) I suspect it's far more interesting than listening to Greg James on a Friday counting this weeks top 14 that are all non movers, because a static top 14 is so exciting isn't it?

I kinda feel sorry for Greg though because it's clear he's passionate about the charts but even he must find it mind numbingly boring to present the chart show these days.