Thanks Paul. It is an interesting question and, as you can probably guess, there is nothing in black and white. No smoking gun. I think I stand with Louis de Bouillé who noted that the general sentiment amongst the exiles in London (probably best placed to know) was that, “they suspected that the royalists sent from London, namely those around the Comte D’Artois and in English pay, may have been equally responsible [as Cadoudal]; this opinion is with merit and I heard confirmation myself from the less than indiscreet chatter of Hyde de Neuville who was then in London and who had come over from France a short time before the plot had been carried out.”

Which means that D'Artois and his circle, flush with British gold, were using it in various schemes to kill Napoleon. Nothing really new in that. There had been Margadel's English Conspiracy which hoped to see Napoleon killed or captured and sent to Jersey; there was the Chevalier de Bruslart scheming in the summer of 1800, another plot in which ambush featured; and Cadoudal had his own ideas for a Chouan-style attack on Napoleon and his escort. I think Saint-Réjant acted on his own initiative in terms of the device deployed, but everyone knew he would make a good bomb-maker and nobody felt it was their duty to stop him.

Plausible deniability all round. Had they managed, then we might have seen more evidence as to the strings that were being pulled.

Sorry this was written in some haste, let me know if you have any questions.