Part of the problem lies with what happened in redrawing Birmingham's constituencies for the 2010 election. The reduction from 11 seats to 10 (9 if you exclude Sutton Coldfield, really a separate community in its own right) was largely caused by a shrinking population in central and southern Birmingham. This caused many of the southern Birmingham constituencies to end up being formed of areas with few proper attachments to each other; the current Birmingham Hall Green is really Birmingham Sparkbrook with the Hall Green ward attached; the current Birmingham Selly Oak has two-thirds of the pre-2010 Hall Green and lacks Moseley & King's Heath, which had been paired with Selly Oak itself for decades in constituency terms. The northern Birmingham constituencies (Edgbaston, Perry Barr, and Erdington) fared much better in the last review by comparison.
The Black Country area, which most strongly identifies with the city of Birmingham, includes the four large boroughs of Wolverhampton (also a city, technically), Walsall, Dudley, and Sandwell. It alone stands to lose 2 seats out its current 13, with Birmingham losing 1 seat out of 9 outside Sutton Coldfield, which the Boundary Commission has wisely chosen to leave unchanged, and so it should be.
The size of the council wards in this area of Britain presents serious challenges for creating new constituencies; Birmingham has the largest wards in Britain, larger than even those of Leeds, making ward splitting practically inevitable. However, sensible and minimal ward splits can be carried out when done properly, not only in Birmingham but also Dudley. It is particularly important that natural communities are kept together (there are many small towns in the Black Country) even if this means that ward splits occur somewhere. Had the allowed deviance from the average electoral quota been 10% as opposed to 5%, we would not have this problem.
I have sadly not been able to find a solution which avoids one Birmingham ward being transferred to a constituency based in Sandwell, but using sensible ward splitting I have been able to find a solution which avoids ridiculous combinations like 'Birmingham Selly Oak & Halesowen' and a redrawn version of Birmingham Edgbaston with Sparkbrook ward in it. There are pairs of wards among Birmingham's 40 which should never be separated from each other within the drawing of any new Birmingham constituency, and these are they:
1. Billesley and Brandwood.
2. Springfield and Sparkbrook.
3. Stetchford & Yardley North and South Yardley.
4. Longbridge and Northfield.
5. Harborne and Edgbaston.
6. Selly Oak and Bournville.
Also, it should be clear that any Birmingham constituency involving crossing the M6 motorway should not do so in the east of Birmingham, only in the west.
With these in mind, restoring some old Birmingham constituencies (in expanded form) is possible when done carefully; Hall Green should be reunited with Billesley and Brandwood, and Moseley & Kings Heath should be returned to a Selly Oak constituency, or at least one containing the main parts of Selly Oak. Since Birmingham Erdington is under quota and can realistically only add (part of) Oscott ward, this essentially necessitates Aston ward being separated from Nechells and combined with the current Perry Barr, thus reviving a new version of the pre-1983 constituency of Birmingham Handsworth. The shrinking population in the centre of Birmingham, coupled with the fact that of the outer Birmingham wards, only Quinton is suitable for transfer to a Sandwell-based constituency (it does not contain major Birmingham landmarks, which Soho ward does, for example). This in turn effectively forces the merger of the main Edgbaston area with the main area of Selly Oak, with which Edgbaston has more common interests than Ladywood.
In the four Black Country boroughs, a complete redrawing of the map is really needed outside Wolverhampton, where both Wolverhampton South West and Wolverhampton North East can simply expand to the point where the town of Bilston can be removed from the area for constituency purposes, and given back its own constituency. The same can happen with Wednesbury; the town of West Bromwich itself is entirely in the current West Bromwich East; the current 'West Bromwich West' contains no part of the actual town mentioned in the constituency name but is rather 'Wednesbury & Tipton', in the same way that Warley should be called Smethwick. This is the only constituency any outer Birmingham ward should be added to.
My alternative constituencies for the Greater Birmingham area therefore look like this:
Birmingham Ladywood & Sparkbrook succeeds Birmingham Ladywood. Within Springfield ward it loses polling district DEE to Birmingham Yardley and polling districts DEG, DEH, and DEI to a new version of Birmingham Hall Green, making its actual electorate 77,840 and the changed Birmingham Yardley's new electorate 74,068.
Birmingham Hall Green succeeds Birmingham Selly Oak in practice in this incarnation. The current version of Birmingham Hall Green, really 'Birmingham Hall Green & Sparkbrook', is abolished in this plan, and in my opinion deserves to be. This plan for Birmingham Hall Green essentially restores the pre-2010 version of Birmingham Hall Green (albeit with King's Norton ward also included) and contains polling districts DEG, DEH, and DEI from Springfield ward, making its real electorate 74,700.
Birmingham Handsworth succeeds Birmingham Perry Barr, recreating the 1974-83 constituency of the same name (albeit with Perry Barr and parts of Oscott attached). It contains polling districts CVE, CVG and CVJ of Oscott ward, meaning its actual electorate is 72,624. The changed Birmingham Erdington's electorate is therefore 75,068.
Smethwick succeeds Warley.
Wolverhampton West succeeds Wolverhampton South West.
Wolverhampton East succeeds Wolverhampton North East.
Aldridge, Brownhills, and Bloxwich succeeds Aldridge-Brownhills.
Walsall succeeds Walsall South, taking in all of the main town of Walsall.
West Bromwich succeeds West Bromwich East.
Dudley succeeds Dudley South. It contains polling district X01 of Quarry Bank & Dudley Wood ward, making its actual electorate 72,016 and the changed Stourbridge's new electorate 78,458.
Birmingham Hodge Hill and Sutton Coldfield are both unchanged.
Bilston, Wednesbury, and Birmingham Edgbaston & Selly Oak are all new seats. Bilston is a recreation of a constituency of the same name from 1950-74, albeit with Tipton also included. Wednesbury is a near-exact replica of the 1950-74 version of the old Wednesbury constituency. Birmingham Edgbaston & Selly Oak combines most of the 1983-97 version of Birmingham Edgbaston with the 1983-97 version of Birmingham Selly Oak. Note that the changed Birmingham Northfield takes in polling district CFD from Bournville ward which is south of Middleton Hall Road, making Birmingham Edgbaston & Selly Oak's real electorate 78,416 and the changed Birmingham Northfield's new electorate 71,333.