England's 'dismissive' attitude towards Liverpool has nothing to do with Irish immigrants, nor is it that historical. It started in the 80's during the Thatcher years, when, like a lot of northern towns & cities, Maggie, & her government, pretty much left them to rot & focused everything on the south, especially London. Liverpool suffered more than most mainly because the extreme left wing under Derek Hatton had taken control of the city. In the 60's Merseyside was the place to be. A thriving port, a music scene that was the envy of the world, & very little in the way of unemployment. 2 decades later it was a different story. The Toxteth riots, Heysel, a bankrupt city struggling with poverty, crime, & unemployment. It also prompted something of a 'southern' gloating-fest with Harry Enfield creating characters such as 'Loadsamoney', a big-mouth cockney plasterer who bragged about all the work he had & the size of his wad. Kelvin McKenzie, as you'd expect, loved this character so much that he became a regular feature in The Sun. Then we had the Scousers. A bunch of work-shy, benefit seeking, curly-haired Liverpool lads in shell-suits who were up for a fight anytime, anywhere. They became a national favourite, even in Liverpool it has to be said. Unfortunately though, the parody seemed to be lost on a lot of people who actually believed, in their ignorance, that most people in Merseyside were like that. Then we had Hillsborough. Although there was an enormous amount of sympathy for the city initially, thanks to Kelvin McKenzie & The Sun, a lot of people believed that we Liverpool supporters were responsible for the deaths of our fellow Liverpool fans that day, so the anti-Liverpool agenda gathered up more steam. Then a couple of years after that there was the awful murder of little Jamie Bulger, which once again brought the city to it's knees, & cast another strong negative light over Merseyside & it's people. Coming so soon after the Hillsborough tragedy, it prompted one journalist to label Liverpool as 'self-pity city' as people mourned the death of the little lad. I think what happened after that is that the city became very insular & had a f**k you attitude to outsiders & their prejudices.
This dismissive attitude, I'm glad to say, has slowly eroded over the years. Liverpool is now a very popular tourist attraction, & is a great place for a night out. Of course you've still got those who think we've all got a garage full of stolen hubcaps hidden away somewhere. But we're happy to leave them, & their outdated, stereotypical, attitudes behind.
