I seem to be getting a lot of this recently. I have changed my commute slightly and take this junction from a different direction, and despite being in the primary position I keep getting squeezed out of this lane! The two lanes on approach split to four lanes. However, it is laid out such that the left lane (of the approaching two) is the correct lane for the left three lanes at the junction. Therefore, I am in the correct lane on approach, however, I keep getting forced out of my lane despite being in the primary. I think I will being moving even further over to the right in future on approach to this junction (Super primary). Would this just encourage undertaking?. What do you think? Oh and note the slightly illegal number plate on the trailer!