We would "need" an extension even if the HoC had a position, to actually implement it. There are something like 300 pieces of legislation that to this day need ammending to (what we can only assume) no longer include or reference the EU and it's mechanisms. I don't think anyone in the thread has a firm understanding of what would happen if this didn't occur but it is the opinion of experts and Parliamentarians that this needs to happen before we can leave in any form.