I agree it's a load of boloney that Welsh parents pay and English ones don't. Me and DH paid for our own and that was 33 years ago. (1989.) As has been said, the vast VAST majority of couples will pay for themselves now. Some parents may buy the dress and pay for the flowers and the photographer (for example,) but very few will pay for it all. Most couples won't expect it.
Our DD (now 27,) met a bloke 7 years ago when she was 20, and they moved in together when she left uni. They were engaged to be married within 3 years. The plan was to get married at 25. We felt it was a bit young but her life. She didn't want a massive wedding, and planned on spending around £7K in total. Including the honeymoon. Her DP agreed.
We said, 'cool... So we'll give you say, £2.5K, you can provide £2.5K yourself, and your DP's parents can pay the other £2.5K. They were both fine with this.
All was OK until they mentioned it to HIS showy, OTT, loaddsaaamoney parents. They were quite wealthy - owned 6 properties they didn't lived in and rented out, owned a villa in Florida and one in Spain, and lived in a £800K house in Staffordshire. His dad drove a £50K car, and his mum drove one similar. We are not poor, but not massively wealthy. 7 year old car, small 2 bed semi, (rented,) £50K joint income, and no assets (just about £15-16K in savings.)
His dad went loco and said HIS son was not having a pauper's wedding
He said he wants their wedding in this big fancy hotel he plays golf at, he wants to pay for their honeymoon, and wants to send them for a fortnight to New Zealand, and his mother said they will pay for OUR daughter's wedding dress, and she has her eyes on one, that cost £7,000, just for the dress! 
Both his parents said they will cover the wedding reception/wedding meal, and that 100 people will be coming from their side alone, and it would be £75 a head. So maybe 10 grand just for that. (With the 20 people from our side too.)
Long story short, the whole kit and caboodle that HIS parents wanted came to about £35-40K. Our DD did not want this at all, and her DP was a bit reluctant, but said 'well if they're gonna pay... maybe we should let them.''
Our DD said ' I don't even KNOW 80 of the 100 people they're bringing along, and as they will be paying for it all, they get to invite who they want apparently.'
Anyway, a massive row kicked off, because DH said no WAY are HIS parents paying for our daughter's wedding. We will go halves and pay the amount DD and her DP had settled on. Her DP weakened and said they should let his parents take over, DD said 'maybe we should just let them.. at least WE won't have to pay anything, and neither will you and dad...' They had her sucked in.
DH and I said we would not be going if this happens, as we KNOW it's not what they want, and it's his bolshy, rich parents driving it all, thinking their money will make them get them their own way.
tl;dr they split a few months later, as DD discovered after 3 years together that her DP didn't want children - ever. DD said (a few weeks afrer they split) that it was such a relief to get away from his family really. They were far too different, it would never have worked. HIS parents really were fucking awful. She is now with a man much more suited, (been together 2 years,) and his parents are lovely.