Welcome to Flyertalk Geeza Butler, welcome to the BA forum. I hope you will have a chance to look at the many other threads here, there's a lot of useful (and some useless) information hereabouts.

Given the sparse details, I suspect it falls into the "hard to say" area. If it was a European airline and they are based in Europe, then snow disruption on the outbound sector may be a good reason to not pay compensation. A case of where the details matter. They would still have to pay the taxi fare and reasonable food and drink (etc) as per the Right of Care aspects. It also depends when this was, if was many years ago you may now be too late to claim, and that time frame depends somewhat on where you bought the ticket/where you live.

If it was a USA airline then it's not EC261 you need to look towards, and broadly speaking poor weather anywhere is considered just part of life.