Sobelair must have leased this GB Air 737 for a programme of charter flights from Brussels.  Here it is taxying to stand after arriving from a Sobelair sunspot.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/130275500@N02">G B_NZ</a>
CC BY-SA 2.0
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/130275500@N02/29126442174/">Sobelair 737-200 G-BECH at BRU</a>