Fair enough, but I am hard pressed to see Heswall as part of Liverpool.
Because it's posh? It and West Kirby are only the western version of the posh outer-suburbs you get in the north (Crosby etc), east (Knowsley Village etc) & south (Woolton etc).
As for you're mention of Leigh, it kinda really did get the short straw, being stuck with a much larger town, Wigan, aside the whole Greater Manchester thing.
This side of Wigan North Western, Southport got the poorest deal. While there's an element of anti-Liverpolitanism, the main beef has been with Sefton and the power struggle it has with Bootle. Of course, Bootle isn't fond of the arrangement either, but at least they're not cut off from their immediate neighbours by a narrow corridor of county boundary.
Ideally, I'd like a London-style system for Liverpool, Manchester, Birmingham & possibly Newcastle, with local boroughs and a larger, strategic body for continuity. They'd be larger than the current official city boundaries but smaller than the metropolitan countys they're currently in. In Merseyside's case, I'd take Southport & Formby out of Sefton and merge it with the existing West Lancashire district (Ormskirk, Skelmersdale etc) as a unitary authority. It'd be considered a part of Lancashire. St Helens would have no change, except that it'd be considered a part of Lancashire. The remains of Sefton, Knowsley, Wirral & Liverpool would be part of a Greater Liverpool. The boroughs would remain as they are, although Sefton would take in some parts of northern Liverpool and Knowsley some eastern parts, to balance out the populations. The city would continue to co-operate on a wider regional level with western Cheshire, south-west Lancashire etc, and on even wider scales, such as North West England, North Wales etc where there's common desire or necessity.
A lot more power for city & county halls would be nice too, as well as more town & parish councils.
Nothing to do with trains, but hey ho!