<a href="https://en.wikipedia.org/wiki/National_Express_West_Midlands" class="extiw" title="en:National Express West Midlands">National Express West Midlands</a> 1557 (R557 XOB), a <a href="https://en.wikipedia.org/wiki/Mercedes-Benz_O405" class="extiw" title="en:Mercedes-Benz O405">Mercedes-Benz O405N</a>, at Old Square, <a href="https://en.wikipedia.org/wiki/Birmingham" class="extiw" title="en:Birmingham">Birmingham</a> city centre, on route 120. I assume the E prefix is displayed on the front in error, given the side blinds just say "120", and on checking on the company's website route E120 doesn't seem to exist. Either way, it shows the unusual four-track number blinds these buses have.
<a href="//commons.wikimedia.org/wiki/User:Arriva436" title="User:Arriva436">Arriva436</a>
CC BY 3.0
<span class="int-own-work" lang="en">Own work</span>