This rolls back almost 2 decades to the times that Spokes did comparative counts at Tollcross and other locations, generally finding that cyclists counted around twice as many cycles as general surveyors. the resaon being that cyclists will spot cycles hidden behind larger vehicles, or using a 'safe' route which is not on the traffic survey tick box matrix.
It is reinforced by results from automated counters - typically on the A6 in to Manchester. A 10 hour manual traffic count. 08.00-18.00 completely missed the peak time for cycling which occurred before the main surge in motorised traffic for various reasons (people are passing earlier to beat the traffic/it takes slightly longer to cycle/more cyclists are riding earlier because they have no viable bus or rail service to getting to work for an early shift).
When I lived in Edinburgh and needed to be on site in Greenock for 08.00 I used to catch the 04.50 train to Glasgow. I saw plenty of people cycling but substantially fewer cars and buses, making the % of cyclists in the traffic mix very impressive at 04.45! We had a regular crew for the early trains, including one guy who cycled in from Fordell in Fife on a 3-speed step through with a basket, in his kilt. (he got pulled in one morning - 35mph along Queensferry Road in 30mph limit)