Hi Whingell,
I like to think I've been around a bit but I have never heard of a joint being too close to the standard, unless it interferes with either the standard to ledger connection or the installation of the transom or brace within 300mm of the node.
However; refer your man to TG20:08 Section 9, para 9.2
"Joints in ledgers may be made with sleeve couplers or expanding pins. Where tension is likley to occur, only Class B sleeve couplers should be used. Joints in ledgers on the same lift and in adjacent lifts should not normally occur in the same bay. However, when guardrails are to remain permanently in place, the absence of a joint in the guardrail in any bay may be accepted as giving sufficient continuity to the scaffold to permit joints in ledgers above and below in the same bay. Where joints are necessary they should be positioned at a distance not greater than one third of the span betweeb adjacent standards"
No mention there about minimum distance.
hope this is of help
regards
Alan