In Law "tenour" (BrE) or "tenor" (AmE) means "the exact wording of a document".
Without the full context it is difficult to be sure but "of this tenor/tenour and date" usually means "identical to this one (document)" or "the same as this" (typically used when there are several copies of one document).
Note that in Finance, tenour/tenor means: the time before a bill of exchange etc becomes due for payment
"We are not wholly bad or good, who live our lives under Milk Wood"
prayer of the Reverend Eli Jenkins in Under Milk Wood by Dylan Thomas