I thought people might be interested to know how I came up with the aged "Gander's Holiday Camp" billboard.  So here's the method I used:

Firstly, I searched online for a good photo of Arthur Askey (not easy as photo's of the man himself were largely of him larking about and pulling faces!)

Having found a nice picture - I won't reproduce it here, in the interest of copyright laws - I set about drawing a passable charicature sketch in pen:

As you can see, I overdid Arthur's conk a bit!  However, this was rectifiable at the next step...

I imported the picture to "Phonto" a nice text adding app on my phone.  After doing some cursory research on 1940's - 50's poster typefaces, I experimented with a few styles before settling on a design:

Next, I transferred the design to an app on my tablet - "Autodesk Sketchbook" for editing and refining. 

Step one was to erase the overdone nose-outline, followed by some aging - fading the whole image "transparency" by a few degrees and overlaying some white blotches to simulate peeled paint.

After this, I added a faint skin tone and a pale blue on Tommy's hat - an attempt was made to have brickwork showing through by adding a photo I took of said subject matter under the image:

The result was very pleasing for a home made effort.  The image was then reduced down to a suitable size and printed on ordinary plain white paper.

  It became obvious that at this scale, the brickwork pattern was lost - becoming ill-defined, and obscuring the main image.

So, the brickwork layer was removed and the resulting picture was much more as I imagined it.

The poster was further aged by a dry-brushing of Earth Brown paint around the edges (to soften and blend it in with the patina of the surrounding wall):

In situ, the poster looks very much as intended - although not "painted" directly onto the wall, rather a hand-painted wooden billboard (commissioned many years ago by Tommy himself) mounted in an eye-catching spot, to promote his holiday camp to arriving visitors.

I hope that this was a useful and interesting post.