Controlling Bluetooth Speaker Using a Remote Device

I sometime have to use my portable Bluetooth speaker to listen to music when in a work van with a duff radio. Because it is a multi-drop job I want to pause playback when I get out of the van and resume playback when I get back into the van but the speaker is a bit of a stretch away in a dashboard cubby hole near the windscreen so a bit of a faff to reach its Play/Pause button (the phone itself is safely tucked away in my pocket so not an option).

Finally realised yesterday that all I have to do is to also connect a small Bluetooth headphone adapter (without the headphones plugged in) as well as the speaker to my phone. Clip the adapter to somewhere convenient near the steering wheel and I can then use the Play/Pause button on that to control playback on the speaker. Jobs a good'n.