This might be of interest for some people on here.
Under the freedom of information act I managed to get Hertfordshire police to send me all the locations they have used for mobile speed cameras in 2016.
Next up is Essex, once I get the details I will post it up on this thread.
Street - Locality - Town - Number of tickets issued
A1000 Barnet Road near Wagon Road, Ganwick Corner Potters Bar 77
A1057 Hatfield Road East of Beechwood Avenue St Albans 122
A1057 St Albans Road West near Poplars Avenue Hatfield 8
A1170 High Road near St Catharines Road Broxbourne 160
A1170 High Road South of Slipe Lane Turnford 323
A409 Heathbourne Road North of Clay Lane Bushey 147
A411 Barnet Lane near Edgwarebury Lane Elstree Borehamwood 131
A411 Hempstead Road near Glen Way Watford 17
A411 London Road East of Grange Road Bushey 6
A414 St Albans Road near Longlands Northeast‐bound Hemel Hempstead 132
A414 St Albans Road, near Rant Meadow Westbound Hemel Hempstead 2
A4251 London Road East of Sharpes Lane Bourne End 241
A505 Cambridge Road Southwest of Queenswood Drive Hitchin 41
A505 Letchworth Gate (formerly A6141) Letchworth 2
A5183 Elstree Hill South North of Sullivan Way Southbound Elstree Borehamwood 1003
A5183 Frogmore South of Brinsmead Frogmore St Albans 333
A600 Bedford Road North of Times Close Hitchin 28
A600 Bedford Road South of Deacons Way Hitchin 96
A602 Broadhall Way East of A1072 Gunnels Wood Road Eastbound Stevenage 726
A602 Broadhall Way East of Broadwater Crescent Westbound Stevenage 449
A602 Broadhall Way East of Valley Way Eastbound Stevenage 309
A602 Monkswood Way North of Broadhall Way, Southbound Stevenage 373
B1004 Windhill West of Windhill Old Road Bishops Stortford 69
B1383 Stansted Road near Goodliffe Park Bishops Stortford 191
B1502 Stanstead Road East of Foxholes Avenue Hertford 858
B176 High Street North of Warwick Drive Cheshunt 47
B197 London Road (formerly A6141) near Hillcrest Baldock 240
B197 North Road North of Burymead Stevenage 16
B197 North Road North of Franklins Road Stevenage 86
B4505 Chesham Road Southwest of Hyde Lane Bovingdon 284
B462 Aldenham Road South of Metropolitan Police Club Bushey 552
B4630 Watford Road north of Laburnum Grove Chiswell Green St Albans 127
B487 Redbourn Lane East of Broad Oaks Close, Hatching Green Harpenden 250
B487 Redbourn Lane West of Hammond End Lane Hatching Green Harpenden 11
B488 Icknield Way Northeast of Little Tring Road Tring 10
B5378 Allum Lane near Lodge Avenue Elstree Borehamwood 23
B5378 Shenleybury near Shenleybury Cottages Shenley 18
B556 Mutton Lane near Albemarle Avenue Potters Bar 88
B6426 Cavendish Way near Briars Wood Hatfield 103
B6426 Cavendish Way Northeast of Meadow Dell Hatfield 324
Beech Road near Firbank Road St Albans 58
Bennetts End Road North of Reddings Hemel Hempstead 26
Clovelly Way near Eastbourne Avenue Stevenage 10
Clovelly Way near Scarborough Avenue Stevenage 30
Drakes Drive near Samuel Ryder Academy St Albans 4
Drakes Drive North of Frobisher Road St Albans 140
Drakes Drive, South of Camp Road St Albans 126
Essex Road West of Bingley Road Hoddesdon 3
Goffs Lane outside Goffs School Cheshunt 66
Grace Way North of junction with Vardon Road Stevenage 443
Grace Way North of Sish Lane Stevenage 93
Gresley Way North of Denes Lane footbridge Stevenage 13
Gresley Way Southwest of Woodcock Road Stevenage 6
Hammondstreet Road West of Peakes Lane Cheshunt 252
Hayling Road near Gosforth Lane South Oxhey 6
Hayling Road West of Frinton Close South Oxhey 15
Heronswood Road South of Ridgeway Welwyn Garden City 230
High Street Green near Connaught Close Hemel Hempstead 9
High Street Green South of Farmhouse Lane Hemel Hempstead 31
Howlands East of Howicks Green Welwyn Garden City 56
Howlands East of Linkfield Welwyn Garden City 29
Howlands West of Ascots Lane Welwyn Garden City 1
Leverstock Green Road East of Pancake Lane Hemel Hempstead 226
Leverstock Green Road South of Malus Close Hemel Hempstead 320
Long Chaulden near Varney Road Hemel Hempstead 40
Long Chaulden West of Parkwood Drive Hemel Hempstead 36
Old North Road North of Orchard Road Royston 32
Old North Road South of York Way Royston 14
Park Avenue South of Park Close Bushey 43
Pixmore Way East of Shott Lane Letchworth 18
Radlett Road North of Colonial Way Watford 437
Sandpit Lane junction with Gurney Court Road Eastbound St Albans 4
Sandy Lane near Batchworth Lane Northwood 7
Shenley Road near Meadow Road Borehamwood 91
Shenley Road South of Potters Lane Borehamwood 117
The Common East of Common Gardens Potten End 11
Theobald Street Northwest of Organ Hall Cottages, Southeast‐bound Radlett 7
Tolpits Lane near Scammell Way Watford 22
Woods Avenue near Elm Drive Hatfield 21
Woods Avenue near Oaklands Wood Hatfield 44
Mobile Speed Camera Locations
Re: Mobile Speed Camera Locations
Might see if they'll do this for Cheshire 
Re: Mobile Speed Camera Locations
Also worth asking under the FOI act if they'll tell you which cameras are active and which are decommissions..