Watford were scheduled to send their under-23s to play the non-league club on Saturday, however the Premier League club cancelled the fixture the at 2pm day before.
Welwyn Garden City say Watford's decision to withdraw from a friendly at late notice is an example of "clubs at the elite level having no interest in the way grassroots clubs function".
Welwyn Garden City, who play in the Southern League Division One Central, were hoping for a bumper crowd of up to 400 for the match.
In a statement on the club's Twitter account, the club's press office explained why the cancellation of the match is such a big deal for the club:
"What this means for us as a club? - A huge loss in revenue - we have already paid out for food, drink, programmes, marketing. Along with the obvious loss of what would have been takings on the gate, bar and food hut through not having a fixture."
The club also added, "Please be aware that the whole committee are working on finding a replacement, but this may be difficult at such short notice.
Watford are yet to make a public apology.
August 3, 2018