The aircraft in the OP's link had slats, you can see the left plainly extended.
Thanks Megan. First time I have seen that photo and you are right it did have slats fitted. Obviously owner option.
With only a little over seven hours in the Tiger, the pilot would have had little experience with the aircrafts characteristics, low power, high drag, small speed range, factors pointed out in the report.
That would suggest that whoever certified the pilot as competent to act in command on the TIger Moth neglected to ensure all the factors you mentioned were adequately covered.
The following extract is of interest from the book by Stephen Slater called De Havilland Tiger Moth 1931-1945 (all marks) Owners' Workshop Manual. Page 49-50 refers.
Quote:
"The upper wings of the majority of Tiger Moths are fitted with a further ingenious device to improve low-speed handling. Aerofoil-shaped slats (or 'slots') on the upper wings are held against the leading edge of the wing by air pressure in normal flight, but at speeds below around 60 mph(100kph) they progressively extend by 3in (75mm), encouraging the airflow to remain attached over the top surface of the outer wing, thereby slightly delaying the stall and making it more gentle when it occurs.
The slats which can be manually locked closed by a control on the right side of the rear cockpit, to avoid sudden deployment during aerobatics or unnecessary wear and tear when taxiing - were developed by another British aircraft designer, Sir Frederick Handley-Page. In addition to the cost of the slats and their controls, de Havilland had to pay a royalty of 38 pounds eleven shillings and sixpence on every set fitted as an extra cost option on pre-war Tiger Moths. However, all RAF-specification aeroplanes had them fitted." Unquote.