The details of tonight's top-secret mission for Hobbayne Charity must remain classified to anyone who wasn't there. However, the commander of our very special unit has agreed to answer a few frequently asked questions about a typical GoodGym operation.

How do you get a special forces crew through a small building hosting two council meetings with residents, without being noticed?

Smuggle them through a network of secret corridors.

How do you reduce your greenhouse gas emissions?

Get a couple of GoodGymers to carry away an electricity generator and a canister of diesel, and lend them to a local church.

How do you prepare a charity office for a makeover?

Recruit a team of safe crackers to move the safes out of the painters' way. Or, better, call in GoodGymers to relocate them while keeping all the valuables safely locked inside!

How do you deliver sacks of teddy bears to a social worker supporting children with special needs when you don't know the exact address?

Send in GoodGym Santa and his trusty helper. Santa always finds his way to those who deserve it!

How do you fit long MDF planks into a commercial waste bin?

Call in a GoodGym martial artist to karate-kick them into more manageable pieces.

If you'd like to witness GoodGym's undercover operations first-hand, obviously, we can't tell you where to go. Definitely not to the dark corners of Walpole Park on a Tuesday night (wink, wink).

Did you ever hear of waxcaps? These colourful wild mushrooms love to grow in old, undisturbed grasslands and make a spectacular appearance in autumn. They belong to a group of fungi known for their smooth, thin stems, widely spaced gills and waxy-looking caps, which can be red, yellow, orange, green, pink or white.

Eleven curious GoodGymers were tempted enough to learn more about these incredible mushrooms to forgo their usual Sunday afternoon plans and head to Walpole Park instead. In particularly windy conditions, the GoodGymers joined Richard and two other Ealing Greenwayers for a fungi survey in support of Plantlife – an organisation whose mission is to secure a world rich in wild plants and fungi.

Any activity in Walpole Park this autumn wouldn't be complete without an air of controversy thanks to Ealing Council’s plan for a temporary, 1,200-seat Troubadour theatre, which has sparked strong local opposition. Among the campaigners’ concerns was the loss of green space, whose ecosystem they believe should be protected rather than sacrificed for a large-scale theatre development. Since waxcaps are a rare, species-rich grassland indicator, heavens knew what would happen if the GoodGym and Greenwayer expedition found these fungi in the park!

Armed with flags to mark the locations of the fungi we discovered and litterpickers (to expand our impact beyond mushroom-spotting), we formed a line abreast, standing shoulder to shoulder. We marched forward, eyes firmly fixed on the ground not to miss even the tiniest fungi. Tiny they certainly were - and not quite waxcap-looking.

Our line-abreast phalanx swept through about three-quarters of the park's grassland (and woodchip-land), discovering a variety of fungi and collecting about a bag of litter that hadn't yet been blown away by the wind. No waxcaps, alas!

Walpole Park may not be an ancient grassland, but the hope is not lost. During our quest, we bumped into a shroom-savvy Selborne Society member, who pointed out that the dry summer had been rather merciless to fungi and that he wouldn't expect to find waxcaps in Walpole Park. He gave us some hints about other promising locations, so you may yet see another mushroom survey this autumn, before the first frosty days arrive.

It was already October, and the leaves on many of the trees on Horsenden Hill had turned golden, but everything else around us tried to tell us it wasn't really autumn yet. Short sleeves and sunglasses, rather than a rain jacket, were the right outfit for the mild and windless day at the community farm, where eight Ealing GoodGymers welcomed guests from GoodGym Hammersmith & Fulham and GoodGym Hounslow.

David, who joined us for his first Ealing session, was impressed by the farm's unique and peaceful character and gave us the all-too-familiar line about Perivale's hidden gem.

"I lived all my life in West London and didn't know this place existed!"

We’ve heard it many times, and we know that Horsenden likes to surprise those who eventually get to discover it.

Today's surprise on our way to the two assigned tasks was the new arrival in the horse meadow: Charlie the pony. Last month, we'd been creating a new paddock for him and his companion, Trixie. Since then, the meadow we'd cleared had been fenced off for protection, and new grass had already started to replace the areas cleared of brambles.

The October Horsenden session continued expanding the meadow up the hill. Half of the GoodGymers, the Bramble Team, took loppers, shears and silky saws, not only to cut back blackberries but also to saw through thick branches along the way.

Meanwhile, the other part of the gang, the Rubble Team, transported debris from the car park to fill the gaps in the eroded ditch near the canoe club shed. What we learned later from Ranger Jon Staples was that the idea of using rubble came from the military's riprap - a rocky, loose material laid in a way that helps protect shoreline structures.

The second part of Team Rubble's assignment was to spread mulch over the riprap that had already been laid. In the near future, when a hedge is planted above the rubble and decomposed woodchip, its roots, together with the rocks, will help protect the bank from further erosion, while the hedge will prevent canoeists and visitors from falling into the ditch.

Both teams did a fantastic chunk of hard work that will help the volunteer-led farm thrive. Later in the day, Elsa, the task owner, sent us a lovely message:

"Thank you so much to your team for all the hard work you did today. I don't know if you all realise how valuable it is to us."

If being recognised for impactful work wasn't enough, our team took an hour for an indulgent team lunch with pizza, local soft drinks and craft beer, then marvelled at the tiniest rodents in the whole of Europe - the harvest mice - at Horsenden's Mouse House.

Check our future sessions at Horsenden Farm here.