Vehicle shortages sometimes occur at most garages due to servicing requirements or damaged buses. Orpington had its share of hired vehicles as shown below.
The Bexleybus metroriders first operated at Orpington in their blue & cream livery. Until the larger MRLs arrived for the R1/R11 the short wheelbased MRs were on loan for driver type training and subsequently to help ease the heavy passenger loadings on the St Paul's Cray estate. A few even returned just before the end of Roundabout and these were in full stagecoach livery. Some Robin Hood Ivecos also operated at Orpington in the Bexleybus livery.
London Buses helped with Dodge minibuses A1/A2 and Bristol BL81/85. These acctually ended up staying at Orpington with the BLs recieving Roundabout fleet names. As did MT4 and few Optare OVs from Victoria (GM).
More information can be found on the Fleet List and indeed if you have any information or photos on these below or any others I have missed please let me know