I got this very detailed response from Hadoram to the sandplover issue. Thanks Hadoram!
Well, about your ID case of Charadrius leschenaultii (GSP) versus C. mongolus (LSP), Eilat March 2010. For me it is just normal western race columbinus of GSP, and please note the following 5 key points:
1 JIZZ The legs are located from the mid-body point, producing more horizontal carriage with longer rear end. [In LSP there is usually more pear-shaped posture, with much of body in front of legs, with the impression that legs are located at the rear body.]Overall head structure also better for race columbinus of GSP than to LSP.
2 BILL Despite being columbinus of GSP the bill is still looking strong and heavy with quite-developed gonydeal angle, and it seem quite long too (i.e. a bit longer than the distance between bill base and rear of eye, and with the nail a bit longer than rest of bill. [On LSP bill is normally less robust and with indistinct gonydeal angle, and length approximately equal to distance between bill base and rear of eye, and with nail area shorter than rest of bill, as well as with the mandibles tapering more steeply.]
3 LEGS The tibia clearly long on this bird (and the feet reported to project well beyond tail tip in flight), while the (clean parts) seem light coloured, grey with green tinge - all perfect for GSP. 4 WINGBAR Note rather narrow and less prominent wingbar, and with the rear edge of outer bar being bulges on inner primaries. [The wingbar generally broader on outer secondaries in LSP, and which has fairly straight rear edge on primaries.]
5 TAIL PATTERN The bird seem to have much white in tip/sides of tail and with quite clear dark subterminal bar contrasting with paler basal area - better for GSP, again.