The valuable work "The standards and colours of the army, from the restauration, 1661, to the introduction of the territorial system, 1881", written by Samuel Milne Milne and published in 1893 (only 200 books had been printed) states some inspection reports of infantry and cavalry regiments.
And it seems that the standards had been taken into field until the peninsular war. Milne states on page 103:
"Towards the end of the century regiments ware generally augmented from the six-troop establishment to eight, and in some cases to ten troops, the number of standards being increased to an average of four per regiment, whilst in 1807, when the establishment was at its highest, viz., ten troops, five were used, the 1st Dragoon Guards, with its twelve troops, had no less than six.
Strangely enough, cavalry standards and guidons never obtained the same respect and veneration accorded to those of infantry regiments. Why this should be the case is incapable of explanation; as leading and also regimental rallying points their object apparently was the same. As far as can be ascertained, none were consecrated, no particular ceremony attended their presentation, an when worn out, or too ragged to make a respectable display, they disappeared and new ones took their place without remark."
So, the mention of "ragged standard" seems to be a prove for taking them into the field. A footnote describes some remarks from inspection reports, e.g. "10th Dragoons, inspection, August, 1776. – The two standards bad, received in 1769; the King's standard may last another year; the second standard in rags, and half blown away; standard belts much worse, and look shabby."
In contrast to the above stated Milne writes about the usage of the standards on page 167:
"A close study of inspection returns does not quite clear up the point as to whether all cavalry regiments carried their standards in the field during the earlier phases of the war in the Peninsula.
One thing is certain, they were not carried in 1812, nor in succeeding years; the inspection returns are quite decided upon this head, as the following extracts prove: l1812 half-yearly inspection, 3rd Dragoon Guards, 'no standards in the field'; 4th Dragoon Guards, 'standards left on board the admiral's ship at 'Lisbon'; 1st Royal Dragoons, 'standards with the depot in England', etc. etc."
So, I would assume the British cavalry regiments had their colours in the field during the revolutionary wars.
Greetings from Berlin to Franconia
Markus Stein