A BY 737 was usually operating from most UK regional airports.  Usually operating to Spaninsh resorts in the lmid or late 1970's when this slide was taken.
<a rel="nofollow" class="external text" href="https://www.flickr.com/people/130275500@N02">G B_NZ</a>
<a rel="nofollow" class="external text" href="https://www.flickr.com/photos/130275500@N02/20565450170/">Britannia B737-200 G-AWSY at NCL</a>