I only ever sent one telegram and that was in 1994 or 95 from the Czech Republic when I think ostensibly the post office had pretty much stopped the service in the UK (my parents thought it was a hoax!). What's interesting is that the post office (GPO as was) used lots of great artists to design their telegrams.
Here are three from my stock. The first is by Rowland Emett, who is most noted for his home-spun inventions for the film Chitty Chitty Bang Bang.
This more pastoral one is from Eric Fraser who contributed to the marketing for the Festival of Britain - some interesting thoughts on this from Quad Royal
More frivolously: I have several of these by Ron Atkinson (...surely not the garrulous ex-football manager moonlighting at some ad agency in the 1970s???)