SIC code for a web/mobile app?

[MitchT]

If you launch an app and set up a limited company to administer the business side of the venture, what would the SIC code be? Can't find anything for apps on .gov. Looking at similar companies on Companies House they all seem to be "82990 - Other business support service activities not elsewhere classified". Any ideas?

[MitchT]

It matters in so much as we have to provide one!