Security gates are available with LPS 1175 rating, but tend to look industrial and can cost a lot for something that can be climbed and need a wall, RSJ or ugly metal security fence to hold it.
You may want to consider adapting something residential and bolstering it with a light, alarm, camera and vicious topping, and maybe a steel mesh, and perhaps even plywood on top, especially if you can disguise it.
Ensure hinges are unliftable and ideally behind the gate. If fixings have to be through the gate then use coach bolts.
The usual locking option is a padlock and drop bolt.
Gates should be at the building line to stay visible.
Premier SSL do gates with vertical bars, the SBD G81 to LPS2018 SRB.
The gate is where you will probably want to fix warning signs about CCTV, alarms and dogs.
Padlocks should be to LPS1654 and EN12320 (the latter being an inadequate standard on its own to achieve equivalence to SR3).
LPS1654 requires key security for security levels SR1 to SR8 with 1,000 to 1,000,000 differs. Key security at SR1 is equivalent to BS3621 & BS EN 12320 grade 2, SR2 = BS EN 12320 grade 4, SR 3-SR4 = BS EN 1303 class 4, and SR 5-SR6 = EN BS 1303 class 6. LPS1654 requires protection for a range of times from 1 to 20 minutes against categories of tools for manual attack similar to LPS1175. Tool groups run from A (eg 12” crowbar) to G (eg 5t jack, oxyacetylene cutter, pneumatic drill, 5kw cutoff saw).
At high security domestic level SR3, a padlock would only be expected to see off tools like a 14” boltcropper, hacksaw, gas torch or 7.2V drill for 5 minutes. However, as a padlock puts all the security eggs in one basket and adversaries post-SHTF could carry any size sledgehammer, crowbar and boltcropper, you might want to consider protection up to tool group F and thus look for an SR7 product if anyone ever makes one. The strongest padlock on the market in 2020 has an SR4 rating, and so could presumably be defeated by the additional tools in group D+ like an 18V drill or saw within 10 minutes or group D 12V versions in longer than 10 minutes. LPCB do not allow higher voltage battery tools against padlocks so presumably a 54/60V monster from your local tool warehouse would open it virtually instantly.
The LPS1654 players are Abloy, Squire, Iseo (sold by M Marcus) and Kaba. An LPS1654 SR3 padlock to roughly equates to LPS1175 SR3, and would be something like the:
Squire SS65S LEV3 for £90 (12.7mm Boron open shackle, 1.11kg, 6 pin with 250k differs, CEN5; Squire SS65 LEV3 range is SBD terror rated),
Abloy PL350/25 at £125 (14mm Boron open shackle, 0.93kg, Protec cylinder, CEN5, Sold Secure Gold, EN12320 grade 5, 11 discs), or
Kaba P8065 for £250 (15mm open shackle, CEN5, EN12320 grade 5, SR3 when uses 22 pin Expert, Quattro or Kaba20 cylinder).
For single garden gate scenarios the SS65S sounds like the best value unless you are expecting an amateur locksmith to break in, in which case you can spend more for better key security by upgrading from one row of 6 pins to discs or four rows of pins.
A DormaKaba video shows how cheap padlocks can be opened with a hammer in seconds.
Even the cheapest LPS SR1 padlock costs £50 yet only promises to last one minute against opportunist tools, so maybe do not put much faith in DIY store padlocks which do not even promise to do that. A manufacturer’s ten star rating means nothing without certification. All the more reason to grab an SR3 rated product for £90.
The Abus 83WP/63 (£60) lacks LPS rating but is SBD, Sold Secure Silver and CEN4, weatherproof and can be keyed to match other locks, but is open shackle.
Alternatively you can just look for EN12320 or CEN rated products. EN12320 comes with a seven digit code and the security rating is the last digit, from 1 up to 7, but only measures theoretical strength rather than tool resistance. CEN grades run from 1 to 6 and specify ranges of requirements such as 300-20,000 differs, 0-15kN plug resistance, 0-30Nm torque resistance, 3-100kN pulling resistance, 4—2,500Nm twisting resistance, 6-100kN cutting resistance, -20 – -40 frozen impact resistance, 0-8 minutes drilling resistance and 2-8 minutes sawing resistance. CEN improves on EN12320 in that it tests common attacks, but it still does not test tool groups and CEN ratings are decided by manufacturers, other than Abus who have theirs tested, so perhaps not so reassuring unless maybe they also have a Sold Secure Gold rating like some Federal and Multlocks. You can pick up such a Federal FD740 CEN 5 for £60 with 14mm molybdenum shackle, and CEN ratings of 3 to 6 are available with Sold Secure such as the Abus 83CS/80 with 15mm closed shackle, SS Gold and claiming CEN6 for £240.
SBD approve padlocks, including for terror, and the only SBD CPNI padlocks are among the Squire SS65 range such as the 1.1kg CEN6 £115 Squire M3ARX LEV3 SR3+. SR3 was, until Squire achieved SR4 for its SS100 range in August 2020 which launched in July 2019, the highest rating for padlocks. Even these models can be destroyed with a sledgehammer if against an immovable surface (the case shatters in half), or by an angle grinder, as Bennetts bike security testers have found. SBD can apply to padlocks such as the Sold Secure Bronze Federal FD700 (£40) which is only CEN3, or the FD730 (£45) which is SS Silver and CEN4, or the FD 740 (£138) which is SS Gold and CEN5, so SS or SBD is not necessarily enough on its own (nor is CEN).
Squire claim to have the world’s strongest padlock, the 4.3kg 24t-rated 20mm closed shackle SS100CS at £289 to SBD, CEN6 and SR4, and SS Diamond if with 22mm chain – such as their £400 TC22. It goes with their CEN6 SR4 STH100 padbar at £135, which is the only LPS 1175 padbar. The SS100CS can see off a battery disc grinder for 10 minutes and it took 20 x 50 BMGs, 40 x .308 armour piercing rounds and 60 x .556 from Bosnia Bill and Lockpicking Lawyer to crack it when they tried and only when they hit the shackle enough times with the .50. Unfortunately, it does not come with the more secure cylinders against picking such as the NW4 or R1 that the SS80CS does, and only comes with dual key unlocking, so if you want extra key security with Mauer dimples and sliders, perhaps as you are worried about youtube lockpickers, and just one key, then consider accepting a SR3 rated smaller version such as the SS80 with 16mm shackle (£82 for open shackle), which is still strong as hell.
Abloy can also do a padlock to SR4, the 1.3kg PL662, with 15mm Boron shackle and which is in itself rated SR3, but gets SR4 if used with their PL201 or PL203 locking bar as the PL660 padlock set.
If you do not want a dual key padlock then you are looking at LPS 1175 SR3 padlocks, which include the Abloy PL350 above, the PL362 (£206, closed shackle, EN12320 grade 6), and PL645, PL654 & PL662 (no longer advertised; PL662 is 1.3kg with 15mm Boron shackle); ISEO-Locken P3SA180274M (no longer advertised); Kaba P8065 above), P8093 (15mm closed shackle, CEN6 & EN12320 grade 6); or Squire SS80 above, or SS65CS LEV3 (£114). If you do not need the key security of the Abloy or Kaba then you save a bundle by going for the Squires.
A cheaper rough and ready option is a non insurance rated Sold Secure Gold padlock with an alarm, the Oxford Boss for £90.
Add a Prikka strip topping (or worse), solar PIR light and CCTV for a few quid and you can turn your side gate into a nightmare for anyone looking to sneak round the back.
Adding anti climb paint just completes the burglar’s day nicely.
If you can afford it there are options like a wireless infra red camera with remote screen for around £270 such as the Abus TVAC15000, although there is newer technology nowadays
A normal Brenton padbolt is vulnerable not just to kicking screws out but manipulating the padlock.
Ultimately a padlock may not be enough if you want to stop a 42” boltcropper, angle grinder or a freezer spray & sledgehammer combo, although without a winch or putting the padlock on the ground some can stop boltcroppers and sledgehammers and slow down grinders. The secret is to go for a heavy thick Boron closed shackle model.
Also consider a PJB Security gate lock for £35, which is not rated and is also used a garage door bolt, and bolts through the gate and post, boasting a 70mm throw. Asec do one for £20. The IFAM CR19S does the same thing but with a Euro cylinder and you can get a version with no key for use out of reach. These are long throw gate locks. Gatemaster do rim mounted deadlocks including an Euro profile cylinder deadbolt with 67mm throw for £54. Squire do a weatherproof 4 keybolt for £28.
If you have to use a chain then a sophisticated SBD & SS Bronze rated PIN lock is the Loxal IDACS Block Lock M3.