[Goosegirl]

Mods, this isn't anything to do with anatomy, I'm meaning the regional names of the back paths between a row of terraced houses. In Crewe where I was born we called them the backsies which had little coloured tiles with a central drain.   

[Kleftiwallah]

In Cumbria (if I remember rightly), it could be lane or lonnin or possibly a yard.

In Devises (Wilts) there is also Ginnel (acces to the market). Thanks for reminding me JayG.
Cheers,  Tony.

[mrs bouquet]

We had a "back alley" when we were kids.  Garages were at the bottom of the long gardens, and the alley was the access to them.  But it was a great place to play.  No cars ever used it, so it was good for bikes and scooters etc.  We would have been between 5 and 10 years of age, and so it was safe for us.  Maybe not now though !   Mrs Bouquet

[Subversive_plot]

"Alley" was common in the city where I grew up (Indianapolis). In-city, single-family housing had an alley behind a row of houses, used as an access way for purposes such as garbage collection. There was enough space for garbage cans (no wheelie bins back then) at the edges and a lane for the garbage truck to get through.  Families that blocked the alley did so at their own peril, and with the wrath of the neighbors!

[Lardman]

Entryway or back passage around here.

[JayG]

In Sheffield it's a gennel, in Leeds it's apparently a ginnel (other Yorkshire cities are available but please don't ask me what they call them!  )

[mumofstig]

Gardens/or yards were back to back in East London where I grew up.
As I've moved around Kent, since then, I've only ever known it as the back alley.

[Aunt Sally]

We didn’t have many of them in London where I grew up, but they were probably the ‘back alley’.  I call then a ginnel but that’s probably from watching too many northern soaps on TV.

[MrsPea]

 Down south we call them Twitterns 

[Blewit]

In Nottingham paths between houses were called entries and a connecting path between streets a jitty.

[Yorkie]

The Yorkshire word "snickelway" is a combination of three words:

• Snicket - alleyway (a passageway between walls or fences)
• Ginnel - alleyway (a narrow passageway between or through buildings)
• Alleyway - a narrow street or lane

Make of that what you will 

[Growster...]

There's a 'Twitten' just a few yards away from 'The Turrets', and all it does is make a footpath to cut off the corner on the road. There are a few cottages down there too!

As for the term, "Its origins are not clear, it is suggested it may be a corruption of 'betwixt' and 'between'." We also had one in the village where I grew up. The posts were renewed every now and then by the Parish Council...

[Plot 1 Problems]

[AlaninCarlisle]

In St Helens where I grew up they were called back entries or sometimes just entries. Here in N Cumbria they are referred to as back lonnings