SG12 £5 British South Africa Company Rhodesia Unused with Cert

SG 12 1892 Arms £5 Sage-Green Perf 14x14½ British South Africa Company (Rhodesia) Unused (No Gum) comes with good 2020 KRZYSZTOF CEREMUGA Certificate stating:

"Genuine in all respects, (Examination using VSC-4C Video Spectral Comparator under various wavelengths (IR-VIS-UV) shows NO TRACE of any cancellations or alterations)  Provenance ex BSA archives, part of which was affected by water during World War II London Bombings and hence in (*) condition. Condition: Unused without gum, very fresh" 

The majority of these that are offered as unused have had fiscal cancels cleverly removed and many are also regummed, under close examination no evidence of cleaning or rubbing can be seen or under UV light. I have also closely examined this example and cannot find any sign of a removed cancel or cleaning. These should be purchased only with a certificate from a well respected expert as the majority of these offered are sold without certificates and have been cleaned.