This was a prototype viewing card. However, this may be ambiguous as we don't know if it means 'digital viewing' card or 'digital' viewing card. In contrast to this, there are no other sources or images of this card, meaning this could support our argument.
This was the first viewing card for Sky Digital issued at launch in October 1998.
Yellow House Card2003—2009 (UPGRADE MANDATORY)
This was the third viewing card issued by Sky starting from sometime in 2003. An upgrade to this viewing card was mandatory, so there was various "viewing card exchange" promos in TV ad breaks to alert customers of the changes. These cards can be found commonly on eBay listings for Sky boxes. Kill signals were sent to these cards at the time of the 2009 upgrade, but some people didn't have their boxes powered on at the time, leaving some of these cards still active to this day.
The egg cards didn't last long, as this was the second viewing card for Sky Digital first issued in 1999 when Sky changed their logo to the Helvetica Logo (aka Swoosh Logo).
White Card2009—2015 (UPGRADE MANDATORY)
This viewing card is the most common, found bundled with many Digiboxes on eBay, depending on the seller. An upgrade to this was optional, but Sky still wanted their customers to upgrade so they also made exchange promos for this one. Many people still had their Yellow House cards for awhile.
Gradient Red Card2015—2019
This viewing card was sent to customers who required new ones in mid 2015. It was mostly issued to customers who had recently installed Sky Q, after launching on 9th February 2016.