- A21 between A2218 and A205, Lewisham (Grid ref TQ381720)
- A21 between A205 and A20, Lewisham (Grid ref TQ381750)
- A21 between A2015 and A2218, Lewisham (Grid ref TQ383717)
- A21 between Lewisham boundary and A2015, Lewisham (Grid ref TQ390710)
- A21 between A2212 and Bromley boundary, Bromley (Grid ref TQ398699)
- A21 between A222 and A2212, Bromley (Grid ref TQ403696)
- A21 between A233 and A222, Bromley (Grid ref TQ413680)
- A21 between A232 and A233, Bromley (Grid ref TQ424660)
- A21 between B2158 Farnborough Hill and A232, Bromley (Grid ref TQ450644)
- A21 between B2158 Farnborough Hill and A223, Bromley (Grid ref TQ453640)
- A21 between M25 and A223, Bromley (Grid ref TQ470627)
- A21 between A225 and A25, Kent (Grid ref TQ515540)
- A21 between A26 and B245 R/About, Kent (Grid ref TQ575451)
- A21 between A2014 and A26, Kent (Grid ref TQ590448)
- A21 between A2014 Pembury Road and A2014 Vauxhall Lane, Kent (Grid ref TQ597448)
- A21 between A228 and A2014, Kent (Grid ref TQ609440)
- A21 between A262 and A264, Kent (Grid ref TQ630403)
- A21 between A228 and B2162, Kent (Grid ref TQ652389)
- A21 between B2169 and A262, Kent (Grid ref TQ678370)
- A21 between B2162 and B2169, Kent (Grid ref TQ679354)
- A21 between B2079 and B2169, Kent (Grid ref TQ700331)
- A21 between Kent boundary and B2079, Kent (Grid ref TQ713320)
- A21 between A268 and East Sussex boundary, East Sussex (Grid ref TQ715314)
- A21 between B2099 and B2087, East Sussex (Grid ref TQ716300)
- A21 between B2099 and B2087, East Sussex (Grid ref TQ720295)
- A21 between A229 and B2099, East Sussex (Grid ref TQ730285)
- A21 between A265 and A2290, East Sussex (Grid ref TQ732276)
- A21 between A2100 and A265, East Sussex (Grid ref TQ739250)
- A21 between A2100 and B2089, East Sussex (Grid ref TQ750207)
- A21 between B2244 and B2089, East Sussex (Grid ref TQ759200)
- A21 between A28 and B2244, East Sussex (Grid ref TQ792150)
- A21 between A2101 St Helens Road and A2100 Junction Road, East Sussex (Grid ref TQ800117)
- A21 between A2102 London Road and A2101 St Helen's Road, East Sussex (Grid ref TQ800110)
- A21 between A259 Carlisle Parade/Denmark Place and A2102 London Rd, East Sussex (Grid ref TQ802100)