| Budget-friendly things to do in London this week for £5 or less. The new Bangers in Shoreditch is giving away free breakfast sandwiches.Looking for more free things to do in London? Here are 102 of em! We've also compiled this epic map of free stuff in London. Coo over beautiful William Morris wallpapers The Art of Wallpaper is a new exhibition at Hammersmith's William Morris Society, showing off various Morris patterns borrowed from the collection of Sanderson Design Group. Morris's wallpaper designs are placed within the context of the radical changes in taste witnessed during the Victorian era. Various events and talks take place during the show's run, as well. £3.50 museum entry, which includes this exhibition, until 11 August. Be enchanted by kaleidoscopic images of London Anne Desmet has sliced up her wood-engravings, linocuts and hand-drawn lithographs of London to create new, kaleidoscopic versions of the. original artworks, as part of a new show at Guildhall Art Gallery in the City. There are 41 of these London prints — including 'Fires of London', created with 18 razor-clam shells — plus over 100 others, on display. Pay what you can, until 8 September. The spotlight is thrown on wallpapers at the William Morris Society. Image: David Hawgood via creative commonsFind out about the geopolitics of climate change As well as posing a threat to health and habitats around the world, climate change is also likely to trigger geopolitical instability. Tuesday's Gresham College lecture by Professor Myles Allen delves into some of these threats, focusing specifically on international tensions over solar geo-engineering (reflecting sunlight away to modify temperatures). Watch in person at Barnard's Inn Hall, or online — both are free. Free, 16 April. Watch free synchronised swimming displays If you find yourself in Covent Garden on Wednesday, swing by the Piazza to see displays of artistic swimming (or synchronised swimming, as most people know it). Professionals of the sport show off their manoeuvres in a specially-built tank every half hour or so. Olympic British athletes Mo Farah and Greg Rutherford are expected to make an appearance. Why? To mark 100 days until the Paris Olympics. Oh, you mean why are two track athletes turning up to a swimming event? No idea, but we're not sure they'll be slipping into their budgie smugglers and taking the plunge themselves. Free, 17 April. Get breakfast at a 'greaseless spoon' cafe Breville is showing off its latest air fryer, courtesy of a pop-up 'greaseless spoon' cafe at Bubba Oasis in Angel, where they're doling out full Englishes for free (there are veggie and vegan options too). You'll need to book a slot for this one. Free, 17 April. London has a 'greaseless spoon' cafe for one day only.Learn about the man who changed shipping Learn about John Marshall — the man who reformed Lloyd's Register — in a free talk at Guildhall Library, which can be watched in person or online. Marshall owned a fleet of 30 ships in the 19th century, and made and lost his fortune three times. He instigated the reform of Lloyd's Register, which upholds standards of design, manufacture, construction and maintenance in the shipping industry. Free, 17 April. Take a tour of Shardlake’s London Follow in the footsteps of fictional lawyer and detective Matthew Shardlake, in this free talk about the tensions and troubles of 16th century London, discussing locations such as Staple Inn, Holborn and Walbrook. Watch in person at Guildhall Library, or online. Free, 18 April. Go Behind the Blue Doors in Brixton Recognise the building above? Perhaps you've passed by and wondered what's Behind the Blue Doors? A new exhibition of that name reveals all. Head to the Lambeth Archives to see documentary photographer Jim Grover's photos of the residents of Trinity Homes Almshouse, and learn about the people — past and present — who've called it home. Stories range from the first residents in the 1830s, to the first male resident, to a former footman at Buckingham Palace who still lives here today. Free, 19 April-1 June. Bear witness to prisoners of war Tying in with its current Great Escapes exhibition, the National Archives hosts a talk about stories of survival from the second world war. Collection specialists and authors Will Butler, Roger Kershaw and Ela Kaczmarksa discuss experiences of both civilians and prisoners of war who were kept in internment camps £5, 19 April. Be inspired at the free AdventurHER exhibition Group tour company Intrepid Travel opens a free exhibition telling the stories of 11 female adventurers, including presenter and journalist, Louise Minchin, who took on the Patagonman Triathlon, and Kelda Wood, the first para-rower to solo row across the Atlantic. See it at 20-22 Camden Passage, Islington, N1 8ED. Free, 19-21 April. Get yourself a free breakfast sandwich More free breakfast! Food delivery service Bangers opens its first physical store this week — and it's giving away free food to celebrate. 100 breakfast sandwiches (original or veggie) are being given away every day, from Friday 19 April-Sunday 21 April, at the new venue in Shoreditch (5 Leonard Circus, EC2A 4DQ). The freebies are likely to be popular so we recommend getting down there early: opening times are 7.30am-2.30pm, every day from 19 April. Free, 19-21 April. Immerse yourself in London's art world Join our lovely community of London art-lovers over on our Urban Palette newsletter — with free weekly reads sent out every Monday rounding up some of the biggest news, reviews, interviews and insights from London's art world and plenty of (also free!) opportunities to meet up at exhibitions around the city. Sign up here or in the box above to become part of the community. Celebrate Eid in Trafalgar Square Trafalgar Square's the setting for Eid in the Square, London's official Eid celebration, marking the end of Ramadan for the Muslim community, which takes place on Saturday. Market stalls, live performances and family-friendly activities are going on throughout the afternoon, with everyone welcome to attend. Find out about other Ramadan and Eid events in London this year too. Free, 20 April. Watch the London Marathon Photo: DanHuddleston via creative commonsIf you're in London on Sunday, it'll be hard to miss the London Marathon. The mass participation running event has thousands of runners, following a 26.2 mile course from Blackheath to Buckingham Palace, via Woolwich, Rotherhithe, Canary Wharf and the Isle of Dogs. Naturally, it's free to watch anywhere along the route, so why not get out there and cheer the runners on — and look out for costumes including a giant telephone, and 10 people in a single bus costume. Celebrities including Romesh Ranganathan, Christopher Eccleston and Ruth Wilson are also taking part. Have a read of our complete guide to the London Marathon for everything you need to know. And whether you're watching, taking part, or swerving it all together, be aware of widespread road closures along the route all weekend. Free, 21 April. Celebrate St George’s Day in Trafalgar Square As if central London won't be busy enough on Sunday with the London Marathon (above), there's also the St George's Day Festival taking place in Trafalgar Square (which has a quick turn around from Saturday's Eid celebrations). The free party for England's patron saint is open to all, with live entertainment and activities all afternoon. The Pearly Kings and Queens will be in attendance, along with Morris dancers, sea shanty singers and plenty more. It's family-friendly. Free, 21 April. | 